To provide a user discrimination device provided with a guest room in which a lock mechanism is controlled and enhancing a reliability of an access to a car.

The user discrimination device has a transmittance circuit part E1 and a receiving circuit part R1 and is provided with a discrimination circuit C1 and a discrimination sub circuit B1 which a user possesses. When a distance between the discrimination circuit and the discrimination sub circuit is not more than a predetermined limitation, a transmittance/receipt of a discrimination code is carried out and an access can be carried out only when the discrimination circuit certifies the discrimination sub circuit. In order that a repeater which is not certified is inserted and a transmittance/receipt of a discrimination data from the outside of the predetermined limitation is prevented, the discrimination device is provided with two way switches 12, 25 switched so as to temporarily establish a feed back loop. The discrimination circuit is provided with a discrimination management unit 20 for measuring a vibration resonance frequency. The discrimination management unit 20 detects a difference between the vibration resonance frequency and a standard resonance frequency and when the difference exceeds a predetermined value, an access can be rejected.