diff --git a/README-ja.md b/README-ja.md
index 6257adf7..5c4630b1 100644
--- a/README-ja.md
+++ b/README-ja.md
@@ -48,6 +48,7 @@
 
 - Environment、AWS region、IAM role は `workflow-config.yaml` で定義する。環境の追加・削除は同ファイルの編集で行う。
 - 認証は GitHub OIDC。`aws/github-oidc-auth/` が environment ごとの plan / apply role を発行し、executor がそれを引き受ける。
+- GitHub environment `production` は tag pattern `*-v*` に一致する ref からの deployment だけを受け付ける。この設定は `github/repository/` で管理する。
 - Terragrunt の remote state は S3 + DynamoDB に保存される。bucket / lock table 名は各 `aws/{service}/root.hcl`（および `github/` 配下の同等ファイル）で定義される。
 
 ### Pipeline Flow
diff --git a/README.md b/README.md
index a7d2ee81..988eaad5 100644
--- a/README.md
+++ b/README.md
@@ -48,6 +48,7 @@ A PR labeled by `panicboat/deploy-actions` is resolved against `workflow-config.
 
 - Environments, AWS regions, and IAM roles are defined in `workflow-config.yaml`. Adding or removing an environment means editing that file.
 - Authentication uses GitHub OIDC. `aws/github-oidc-auth/` issues per-environment plan / apply roles that the executors assume.
+- The GitHub environment `production` accepts deployments only from refs that match the tag pattern `*-v*`. The setting is managed in `github/repository/`.
 - Terragrunt remote state lives in S3 + DynamoDB; bucket and lock-table names are defined in each `aws/{service}/root.hcl` (and the equivalent under `github/`).
 
 ### Pipeline Flow
diff --git a/github/repository/master/platform.hcl b/github/repository/master/platform.hcl
index ee248241..7933f3a1 100644
--- a/github/repository/master/platform.hcl
+++ b/github/repository/master/platform.hcl
@@ -9,5 +9,6 @@ locals {
       wiki     = false
       projects = true
     }
+    environments = { production = { deployment_tag_patterns = ["*-v*"] } }
   }
 }
diff --git a/github/repository/modules/main.tf b/github/repository/modules/main.tf
index d52908d2..130db629 100644
--- a/github/repository/modules/main.tf
+++ b/github/repository/modules/main.tf
@@ -38,3 +38,36 @@ resource "github_workflow_repository_permissions" "repository" {
   default_workflow_permissions     = "read"
   can_approve_pull_request_reviews = false
 }
+
+resource "github_repository_environment" "repository" {
+  for_each = merge([
+    for repo_key, repo in var.repositories : {
+      for env_name, env in repo.environments :
+      "${repo_key}/${env_name}" => { repo_key = repo_key, name = env_name }
+    }
+  ]...)
+
+  repository        = github_repository.repository[each.value.repo_key].name
+  environment       = each.value.name
+  can_admins_bypass = false
+
+  deployment_branch_policy {
+    protected_branches     = false
+    custom_branch_policies = true
+  }
+}
+
+resource "github_repository_environment_deployment_policy" "repository" {
+  for_each = merge([
+    for repo_key, repo in var.repositories : merge([
+      for env_name, env in repo.environments : {
+        for pattern in env.deployment_tag_patterns :
+        "${repo_key}/${env_name}/${pattern}" => { env_key = "${repo_key}/${env_name}", pattern = pattern }
+      }
+    ]...)
+  ]...)
+
+  repository  = github_repository_environment.repository[each.value.env_key].repository
+  environment = github_repository_environment.repository[each.value.env_key].environment
+  tag_pattern = each.value.pattern
+}
diff --git a/github/repository/modules/tests/environment.tftest.hcl b/github/repository/modules/tests/environment.tftest.hcl
new file mode 100644
index 00000000..a0ddccc4
--- /dev/null
+++ b/github/repository/modules/tests/environment.tftest.hcl
@@ -0,0 +1,106 @@
+mock_provider "aws" {}
+
+mock_provider "github" {}
+
+variables {
+  project_name = "repository"
+  environment  = "master"
+  github_org   = "panicboat"
+  github_token = "dummy"
+}
+
+run "creates_tag_policy_for_declared_environment" {
+  command = plan
+
+  variables {
+    repositories = {
+      platform = {
+        name        = "platform"
+        description = "Platform"
+        visibility  = "public"
+        features = {
+          issues   = true
+          wiki     = false
+          projects = true
+        }
+        environments = {
+          production = { deployment_tag_patterns = ["*-v*"] }
+        }
+      }
+    }
+  }
+
+  assert {
+    condition     = keys(github_repository_environment.repository) == ["platform/production"]
+    error_message = "One environment must exist per declared repository and environment."
+  }
+
+  assert {
+    condition     = github_repository_environment.repository["platform/production"].environment == "production"
+    error_message = "The environment must use the declared name."
+  }
+
+  assert {
+    condition     = github_repository_environment.repository["platform/production"].can_admins_bypass == false
+    error_message = "Admins must not bypass the deployment policy."
+  }
+
+  assert {
+    condition     = github_repository_environment.repository["platform/production"].deployment_branch_policy[0].custom_branch_policies == true
+    error_message = "The environment must restrict deployments with custom policies."
+  }
+
+  assert {
+    condition     = github_repository_environment.repository["platform/production"].deployment_branch_policy[0].protected_branches == false
+    error_message = "The environment must not rely on protected branches."
+  }
+
+  assert {
+    condition     = keys(github_repository_environment_deployment_policy.repository) == ["platform/production/*-v*"]
+    error_message = "One deployment policy must exist per declared tag pattern."
+  }
+
+  assert {
+    condition     = github_repository_environment_deployment_policy.repository["platform/production/*-v*"].tag_pattern == "*-v*"
+    error_message = "The deployment policy must match tags, not branches."
+  }
+
+  assert {
+    condition     = github_repository_environment_deployment_policy.repository["platform/production/*-v*"].environment == "production"
+    error_message = "The deployment policy must target the declared environment."
+  }
+
+  assert {
+    condition     = github_repository_environment_deployment_policy.repository["platform/production/*-v*"].repository == "platform"
+    error_message = "The deployment policy must target the declared repository."
+  }
+}
+
+run "creates_no_environment_by_default" {
+  command = plan
+
+  variables {
+    repositories = {
+      platform = {
+        name        = "platform"
+        description = "Platform"
+        visibility  = "public"
+        features = {
+          issues   = true
+          wiki     = false
+          projects = true
+        }
+      }
+    }
+  }
+
+  assert {
+    condition     = length(github_repository_environment.repository) == 0
+    error_message = "No environment must exist when environments is not declared."
+  }
+
+  assert {
+    condition     = length(github_repository_environment_deployment_policy.repository) == 0
+    error_message = "No deployment policy must exist when environments is not declared."
+  }
+}
diff --git a/github/repository/modules/variables.tf b/github/repository/modules/variables.tf
index 29bb0879..1b2d859c 100644
--- a/github/repository/modules/variables.tf
+++ b/github/repository/modules/variables.tf
@@ -43,6 +43,7 @@ variable "repositories" {
       wiki     = bool
       projects = bool
     })
+    environments = optional(map(object({ deployment_tag_patterns = list(string) })), {})
   }))
 }