diff --git a/Cargo.lock b/Cargo.lock
index b4ebf7389..34fa66b6e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1001,6 +1001,27 @@ dependencies = [
  "termcolor",
 ]
 
+[[package]]
+name = "errno"
+version = "0.2.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f639046355ee4f37944e44f60642c6f3a7efa3cf6b78c78a0d989a8ce6c396a1"
+dependencies = [
+ "errno-dragonfly",
+ "libc",
+ "winapi",
+]
+
+[[package]]
+name = "errno-dragonfly"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "aa68f1b12764fab894d2755d2518754e71b4fd80ecfb822714a1206c2aab39bf"
+dependencies = [
+ "cc",
+ "libc",
+]
+
 [[package]]
 name = "event-listener"
 version = "2.5.3"
@@ -1566,12 +1587,34 @@ dependencies = [
  "cfg-if",
 ]
 
+[[package]]
+name = "io-lifetimes"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e7d6c6f8c91b4b9ed43484ad1a938e393caf35960fce7f82a040497207bd8e9e"
+dependencies = [
+ "libc",
+ "windows-sys 0.42.0",
+]
+
 [[package]]
 name = "ipnet"
 version = "2.7.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "30e22bd8629359895450b59ea7a776c850561b96a3b1d31321c1949d9e6c9146"
 
+[[package]]
+name = "is-terminal"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "28dfb6c8100ccc63462345b67d1bbc3679177c75ee4bf59bf29c8b1d110b8189"
+dependencies = [
+ "hermit-abi 0.2.6",
+ "io-lifetimes",
+ "rustix",
+ "windows-sys 0.42.0",
+]
+
 [[package]]
 name = "isahc"
 version = "0.9.14"
@@ -1722,6 +1765,12 @@ dependencies = [
  "cc",
 ]
 
+[[package]]
+name = "linux-raw-sys"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f051f77a7c8e6957c0696eac88f26b0117e54f52d3fc682ab19397a8812846a4"
+
 [[package]]
 name = "lock_api"
 version = "0.4.9"
@@ -2638,6 +2687,20 @@ dependencies = [
  "semver 1.0.14",
 ]
 
+[[package]]
+name = "rustix"
+version = "0.36.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d4fdebc4b395b7fbb9ab11e462e20ed9051e7b16e42d24042c776eca0ac81b03"
+dependencies = [
+ "bitflags",
+ "errno",
+ "io-lifetimes",
+ "libc",
+ "linux-raw-sys",
+ "windows-sys 0.42.0",
+]
+
 [[package]]
 name = "rustls"
 version = "0.20.6"
@@ -3533,6 +3596,7 @@ name = "voicevox_core_c_api"
 version = "0.0.0"
 dependencies = [
  "anyhow",
+ "is-terminal",
  "libc",
  "once_cell",
  "pretty_assertions",
diff --git a/crates/voicevox_core_c_api/Cargo.toml b/crates/voicevox_core_c_api/Cargo.toml
index 47f6ebf4c..695243267 100644
--- a/crates/voicevox_core_c_api/Cargo.toml
+++ b/crates/voicevox_core_c_api/Cargo.toml
@@ -13,6 +13,7 @@ directml = ["voicevox_core/directml"]
 
 [dependencies]
 voicevox_core.workspace = true
+is-terminal = "0.4.2"
 libc = "0.2.134"
 once_cell.workspace = true
 serde_json.workspace = true
diff --git a/crates/voicevox_core_c_api/src/lib.rs b/crates/voicevox_core_c_api/src/lib.rs
index 7ac2b38b9..195f510ba 100644
--- a/crates/voicevox_core_c_api/src/lib.rs
+++ b/crates/voicevox_core_c_api/src/lib.rs
@@ -2,13 +2,15 @@
 mod compatible_engine;
 mod helpers;
 use self::helpers::*;
+use is_terminal::IsTerminal;
 use libc::c_void;
 use once_cell::sync::Lazy;
+use std::env;
 use std::ffi::{CStr, CString};
+use std::io::{self, Write};
 use std::os::raw::c_char;
 use std::ptr::null;
 use std::sync::{Mutex, MutexGuard};
-use std::{env, io};
 use tracing_subscriber::EnvFilter;
 use voicevox_core::AudioQueryModel;
 use voicevox_core::Result;
@@ -20,16 +22,35 @@ use rstest::*;
 type Internal = VoicevoxCore;
 
 static INTERNAL: Lazy<Mutex<Internal>> = Lazy::new(|| {
-    let _ = tracing_subscriber::fmt()
-        .with_env_filter(if env::var_os(EnvFilter::DEFAULT_ENV).is_some() {
-            EnvFilter::from_default_env()
-        } else {
-            "error,voicevox_core=info,voicevox_core_c_api=info,onnxruntime=info".into()
-        })
-        .with_writer(io::stderr)
-        .try_init();
-
-    Internal::new_with_mutex()
+    let _ = init_logger();
+    return Internal::new_with_mutex();
+
+    fn init_logger() -> std::result::Result<(), impl Sized> {
+        tracing_subscriber::fmt()
+            .with_env_filter(if env::var_os(EnvFilter::DEFAULT_ENV).is_some() {
+                EnvFilter::from_default_env()
+            } else {
+                "error,voicevox_core=info,voicevox_core_c_api=info,onnxruntime=info".into()
+            })
+            .with_ansi(out().is_terminal() && env_allows_ansi())
+            .with_writer(out)
+            .try_init()
+    }
+
+    fn out() -> impl IsTerminal + Write {
+        io::stderr()
+    }
+
+    fn env_allows_ansi() -> bool {
+        // https://docs.rs/termcolor/1.2.0/src/termcolor/lib.rs.html#245-291
+        // ただしWindowsではPowerShellっぽかったらそのまま許可する。
+        // ちゃんとやるなら`ENABLE_VIRTUAL_TERMINAL_PROCESSING`をチェックするなり、そもそも
+        // fwdansiとかでWin32の色に変換するべきだが、面倒。
+        env::var_os("TERM").map_or(
+            cfg!(windows) && env::var_os("PSModulePath").is_some(),
+            |term| term != "dumb",
+        ) && env::var_os("NO_COLOR").is_none()
+    }
 });
 
 pub(crate) fn lock_internal() -> MutexGuard<'static, Internal> {