diff --git a/bench/rpxy.toml b/bench/rpxy.toml
index 9eedbc8..4c80774 100644
--- a/bench/rpxy.toml
+++ b/bench/rpxy.toml
@@ -14,7 +14,11 @@ server_name = 'localhost'
 reverse_proxy = [
   # default destination if path is not specified
   # Array for load balancing
-  { upstream = [{ location = 'backend-nginx', tls = false }] },
+  { upstream = [
+    { location = 'backend-nginx', tls = false, upstream_options = [
+      "override_host",
+    ] },
+  ] },
   # { upstream = [{ location = '192.168.100.100', tls = false }] },
 ]
 
diff --git a/config-example.toml b/config-example.toml
index 61e14e9..1544ee3 100644
--- a/config-example.toml
+++ b/config-example.toml
@@ -37,10 +37,14 @@ reverse_proxy = [
   { upstream = [
     { location = 'www.google.com', tls = true },
     { location = 'www.google.co.jp', tls = true },
+  ], upstream_options = [
+    "override_host",
   ] },
   { path = '/maps', upstream = [
     { location = 'www.bing.com', tls = true },
     { location = 'www.bing.co.jp', tls = true },
+  ], upstream_options = [
+    "override_host",
   ] },
 ]
 # Optional: TLS setting. if https_port is specified and tls is true above, this must be given.
diff --git a/src/config/parse.rs b/src/config/parse.rs
index a9e4022..74159a8 100644
--- a/src/config/parse.rs
+++ b/src/config/parse.rs
@@ -1,8 +1,14 @@
 use super::toml::{ConfigToml, ReverseProxyOption};
-use crate::{backend::*, constants::*, error::*, globals::*, log::*};
+use crate::{
+  constants::*,
+  error::*,
+  globals::*,
+  log::*,
+  proxy::{Backend, Backends, ReverseProxy, Upstream, UpstreamOption},
+};
 use clap::Arg;
 use parking_lot::Mutex;
-use rustc_hash::FxHashMap as HashMap;
+use rustc_hash::{FxHashMap as HashMap, FxHashSet as HashSet};
 use std::net::SocketAddr;
 
 // #[cfg(feature = "tls")]
@@ -165,7 +171,18 @@ fn get_reverse_proxy(rp_settings: &[ReverseProxyOption]) -> Result<ReverseProxy>
       uri: rpo.upstream.iter().map(|x| x.to_uri().unwrap()).collect(),
       cnt: Default::default(),
       lb: Default::default(),
+      opts: {
+        if let Some(opts) = &rpo.upstream_options {
+          opts
+            .iter()
+            .filter_map(|str| UpstreamOption::try_from(str.as_str()).ok())
+            .collect::<HashSet<UpstreamOption>>()
+        } else {
+          Default::default()
+        }
+      },
     };
+
     if rpo.path.is_some() {
       upstream.insert(rpo.path.as_ref().unwrap().to_owned(), elem);
     } else {
diff --git a/src/config/toml.rs b/src/config/toml.rs
index 9c6e945..b7ecb7b 100644
--- a/src/config/toml.rs
+++ b/src/config/toml.rs
@@ -40,15 +40,16 @@ pub struct TlsOption {
 #[derive(Deserialize, Debug, Default)]
 pub struct ReverseProxyOption {
   pub path: Option<String>,
-  pub upstream: Vec<UpstreamOption>,
+  pub upstream: Vec<UpstreamParams>,
+  pub upstream_options: Option<Vec<String>>,
 }
 
 #[derive(Deserialize, Debug, Default)]
-pub struct UpstreamOption {
+pub struct UpstreamParams {
   pub location: String,
   pub tls: Option<bool>,
 }
-impl UpstreamOption {
+impl UpstreamParams {
   pub fn to_uri(&self) -> Result<hyper::Uri> {
     let mut scheme = "http";
     if let Some(t) = self.tls {
diff --git a/src/main.rs b/src/main.rs
index dff5a69..cc034f4 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -2,7 +2,6 @@
 #[global_allocator]
 static GLOBAL: tikv_jemallocator::Jemalloc = tikv_jemallocator::Jemalloc;
 
-mod backend;
 mod config;
 mod constants;
 mod error;
@@ -11,13 +10,12 @@ mod log;
 mod proxy;
 
 use crate::{
-  backend::{Backend, Backends},
   config::parse_opts,
   constants::*,
   error::*,
   globals::*,
   log::*,
-  proxy::Proxy,
+  proxy::{Backend, Backends, Proxy},
 };
 use futures::future::select_all;
 use hyper::Client;
diff --git a/src/backend.rs b/src/proxy/backend.rs
similarity index 97%
rename from src/backend.rs
rename to src/proxy/backend.rs
index d5f56ee..62189e7 100644
--- a/src/backend.rs
+++ b/src/proxy/backend.rs
@@ -1,7 +1,8 @@
+use super::UpstreamOption;
 use crate::log::*;
 use parking_lot::Mutex;
 use rand::Rng;
-use rustc_hash::FxHashMap as HashMap;
+use rustc_hash::{FxHashMap as HashMap, FxHashSet as HashSet};
 use std::{
   fs::File,
   io::{self, BufReader, Cursor, Read},
@@ -53,6 +54,7 @@ pub struct Upstream {
   pub uri: Vec<hyper::Uri>,
   pub lb: LoadBalance,
   pub cnt: UpstreamCount, // counter for load balancing
+  pub opts: HashSet<UpstreamOption>,
 }
 
 #[derive(Debug, Clone, Default)]
diff --git a/src/proxy/backend_opt.rs b/src/proxy/backend_opt.rs
new file mode 100644
index 0000000..4ae60bb
--- /dev/null
+++ b/src/proxy/backend_opt.rs
@@ -0,0 +1,16 @@
+use crate::error::*;
+
+#[derive(Debug, Clone, Hash, Eq, PartialEq)]
+pub enum UpstreamOption {
+  OverrideHost,
+  // TODO: Adds more options for heder override
+}
+impl TryFrom<&str> for UpstreamOption {
+  type Error = anyhow::Error;
+  fn try_from(val: &str) -> Result<Self> {
+    match val {
+      "override_host" => Ok(Self::OverrideHost),
+      _ => Err(anyhow!("Unsupported header option")),
+    }
+  }
+}
diff --git a/src/proxy/mod.rs b/src/proxy/mod.rs
index 20b5810..5acb8f1 100644
--- a/src/proxy/mod.rs
+++ b/src/proxy/mod.rs
@@ -1,7 +1,11 @@
+mod backend;
+mod backend_opt;
 #[cfg(feature = "h3")]
 mod proxy_h3;
 mod proxy_handler;
 mod proxy_main;
 mod proxy_tls;
 
+pub use backend::*;
+pub use backend_opt::UpstreamOption;
 pub use proxy_main::Proxy;
diff --git a/src/proxy/proxy_handler.rs b/src/proxy/proxy_handler.rs
index a60eb25..bd7c4eb 100644
--- a/src/proxy/proxy_handler.rs
+++ b/src/proxy/proxy_handler.rs
@@ -1,5 +1,5 @@
 // Highly motivated by https://github.com/felipenoris/hyper-reverse-proxy
-use super::Proxy;
+use super::{Proxy, Upstream, UpstreamOption};
 use crate::{constants::*, error::*, log::*};
 use hyper::{
   client::connect::Connect,
@@ -68,14 +68,14 @@ where
     // Find reverse proxy for given path and choose one of upstream host
     // TODO: More flexible path matcher
     let path = req.uri().path();
-    let upstream_uri = if let Some(upstream) = backend.reverse_proxy.upstream.get(path) {
-      upstream.get()
+    let upstream = if let Some(upstream) = backend.reverse_proxy.upstream.get(path) {
+      upstream
     } else if let Some(default_upstream) = &backend.reverse_proxy.default_upstream {
-      default_upstream.get()
+      default_upstream
     } else {
       return http_error(StatusCode::NOT_FOUND);
     };
-    let upstream_scheme_host = if let Some(u) = upstream_uri {
+    let upstream_scheme_host = if let Some(u) = upstream.get() {
       u
     } else {
       return http_error(StatusCode::INTERNAL_SERVER_ERROR);
@@ -92,6 +92,7 @@ where
       upstream_scheme_host,
       path_and_query,
       &upgrade_in_request,
+      upstream,
     ) {
       req
     } else {
@@ -184,6 +185,7 @@ fn generate_request_forwarded<B: core::fmt::Debug>(
   upstream_scheme_host: &Uri,
   path_and_query: String,
   upgrade: &Option<String>,
+  upstream: &Upstream,
 ) -> Result<Request<B>> {
   debug!("Generate request to be forwarded");
 
@@ -206,11 +208,27 @@ fn generate_request_forwarded<B: core::fmt::Debug>(
   remove_hop_header(headers);
   // X-Forwarded-For
   add_forwarding_header(headers, client_addr)?;
+
   // Add te: trailer if te_trailer
   if te_trailers {
     headers.insert("te", "trailer".parse().unwrap());
   }
 
+  // add "host" header of original server_name if not exist (default)
+  if req.headers().get(hyper::header::HOST).is_none() {
+    let org_host = req.uri().host().unwrap_or("none").to_owned();
+    req.headers_mut().insert(
+      hyper::header::HOST,
+      HeaderValue::from_str(org_host.as_str()).unwrap(),
+    );
+  };
+
+  // apply upstream-specific headers given in upstream_option
+  let headers = req.headers_mut();
+  println!("before {:?}", headers);
+  apply_upstream_options_to_header(headers, client_addr, upstream_scheme_host, upstream)?;
+  println!("after {:?}", req);
+
   // update uri in request
   *req.uri_mut() = Uri::builder()
     .scheme(upstream_scheme_host.scheme().unwrap().as_str())
@@ -223,7 +241,7 @@ fn generate_request_forwarded<B: core::fmt::Debug>(
     req.headers_mut().insert("upgrade", v.parse().unwrap());
     req
       .headers_mut()
-      .insert("connection", HeaderValue::from_str("upgrade")?);
+      .insert(hyper::header::CONNECTION, HeaderValue::from_str("upgrade")?);
   }
 
   // Change version to http/1.1 when destination scheme is http
@@ -237,8 +255,29 @@ fn generate_request_forwarded<B: core::fmt::Debug>(
   Ok(req)
 }
 
+fn apply_upstream_options_to_header(
+  headers: &mut HeaderMap,
+  _client_addr: SocketAddr,
+  upstream_scheme_host: &Uri,
+  upstream: &Upstream,
+) -> Result<()> {
+  upstream.opts.iter().for_each(|opt| match opt {
+    UpstreamOption::OverrideHost => {
+      let upstream_host = upstream_scheme_host.host().unwrap();
+      headers
+        .insert(
+          hyper::header::HOST,
+          HeaderValue::from_str(upstream_host).unwrap(),
+        )
+        .unwrap();
+    }
+  });
+  Ok(())
+}
+
 fn add_forwarding_header(headers: &mut HeaderMap, client_addr: SocketAddr) -> Result<()> {
-  // TODO: Option対応？
+  // default process
+  // optional process defined by upstream_option is applied in fn apply_upstream_options
   let client_ip = client_addr.ip();
   match headers.entry("x-forwarded-for") {
     hyper::header::Entry::Vacant(entry) => {
diff --git a/src/proxy/proxy_main.rs b/src/proxy/proxy_main.rs
index 22434d5..3c35693 100644
--- a/src/proxy/proxy_main.rs
+++ b/src/proxy/proxy_main.rs
@@ -1,5 +1,6 @@
 // use super::proxy_handler::handle_request;
-use crate::{backend::Backends, error::*, globals::Globals, log::*};
+use super::Backends;
+use crate::{error::*, globals::Globals, log::*};
 use hyper::{
   client::connect::Connect, server::conn::Http, service::service_fn, Body, Client, Request,
 };