gitHubにssh接続できない

Githubのsshで何故か**Permission denied (publickey)**とエラーが発生してしまいます。

-sh-4.1$ ssh -T git@github.com
Permission denied (publickey).
-sh-4.1$ eval "$(ssh-agent -s)"
Agent pid 29408
-sh-4.1$ ssh-add ~/.ssh/id_rsa
Identity added: 　(省略).ssh/id_rsa

このように、秘密鍵は正常に登録されています。

また「ssh -vT git@github.com」のコマンドを打つと以下のようなコマンドが表示されエラーが発生してしまいます。
どのような対応をした方が良いでしょうか？

ssh -vT git@github.com
OpenSSH_5.3p1, OpenSSL 1.0.1e-fips 11 Feb 2013
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to github.com [52.69.186.44] port 22.
debug1: Connection established.
debug1: identity file /home/t-momokasato/.ssh/id_rsa type 1
debug1: identity file /home/t-momokasato/.ssh/id_rsa-cert type -1
debug1: identity file /home/t-momokasato/.ssh/id_dsa type -1
debug1: identity file /home/t-momokasato/.ssh/id_dsa-cert type -1
debug1: identity file /home/t-momokasato/.ssh/id_ecdsa type -1
debug1: identity file /home/t-momokasato/.ssh/id_ecdsa-cert type -1
debug1: Remote protocol version 2.0, remote software version babeld-cc5efb01
debug1: no match: babeld-cc5efb01
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.3
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr hmac-sha1 none
debug1: kex: client->server aes128-ctr hmac-sha1 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<2048<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host 'github.com' is known and matches the RSA host key.
debug1: Found key in /home/ユーザ/.ssh/known_hosts:5
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey
debug1: Next authentication method: publickey
debug1: Offering public key: 
debug1: Authentications that can continue: publickey
debug1: Offering public key: /home/ユーザ/.ssh/id_rsa
debug1: Authentications that can continue: publickey
debug1: Trying private key: /home/ユーザ/.ssh/id_dsa
debug1: Trying private key: /home/ユーザ/.ssh/id_ecdsa
debug1: No more authentication methods to try.
Permission denied (publickey).