An image forming apparatus includes a memory that stores identification information of authorized users in association with biometric information thereof, a reading device configured to read identification information from a medium, an input device through which biometric information is input, and a processor configured to, upon receipt of one of identification and biometric information, perform a first authentication by determining whether said one of identification and biometric information is stored, when said one of identification and biometric information is stored, upon receipt of the other of identification and biometric information, perform a second authentication by determining whether the other of identification and biometric information is stored in association with said one of identification and biometric information, and when the other of identification and biometric information is stored, enable a first operation that can be performed for the corresponding authorized user.