Provided is a method for controlling an information processing system including a relay service device, an intermediate service device, and an authentication service device. The control method includes transmitting an authentication request from the intermediate service device to the intermediate service device; acquiring a first access token from the authentication service device that has made a success of authentication; storing the first access token; comparing the stored first access token with a second access token included in an execution request of an relation processing upon reception of the processing execution request from the relay service; and executing processing received from the intermediate service device when it is determined in the comparing that the first access token matches the second access token or not executing the processing when it is determined in the comparing that the first access token does not match the second access token.