An endoscope apparatus that includes a storage memory storing first authentication information, a transmitter/receiver that performs communication with an endoscope, and an operational device. The operational device performs a process including acquiring the first authentication information stored in the storage memory and acquiring second authentication information stored in the endoscope connected to the endoscope apparatus from the endoscope. The operational device further performs determining whether the acquired first and second authentication information match each other, and limiting execution of at least some functions among a plurality of functions to be executed in cooperation with the endoscope in response to determining that the first and second authentication information do not match each other.