To provide an online game server and a service method thereof, which are capable of judging each user's competition rank objectively so as to make the user a match to other relevant user in the competition rank.

A game server 10 has a user database 26, to which an ID, a password and a competition rank of each user are recorded. The game server 10 reads the competition rank of a logged-in user from the user database 26 to notify the user. The user, grasping his competition rank, transmits a desired match-up rank to the game server 10, which makes the users of coincident competition rank meet.