diff --git a/README.md b/README.md
index e1ea0299e..04f75ebed 100644
--- a/README.md
+++ b/README.md
@@ -18,6 +18,7 @@ A miniblog-based SNS.
 * Elasticsearch
 
 ## Get started
+### Domains
 Misskey requires two domains called the primary domain and the secondary domain.
 
 * The primary domain is used to provide main service of Misskey.
@@ -25,6 +26,10 @@ Misskey requires two domains called the primary domain and the secondary domain.
 
 **Ensure that the secondary domain is not a subdomain of the primary domain.**
 
+### reCAPTCHA
+Visit and generate keys
+https://www.google.com/recaptcha/intro/
+
 ## Build
 1. `git clone git://github.com/syuilo/misskey.git`
 2. `cd misskey`