PURPOSE: To improve the operability by making so that two switches are turned on individually related to one operation key and discriminating the operational information generated by respective switches from the operational condition at the time.

CONSTITUTION: Two switches 93, 94 are provided on an internal substrate 95 corresponding to a reproducing key 85, and two switches 93, 94 are turned on/off individually. Related to the operation of the reproducing key 85, according to the depressive position, a voltage value different from each other appeares on a terminal 83b in the case when a reproducing/REW switch 93 is turned on and in the case when a reproducing/FF switch 94 is turned on. The voltage value on the terminal 83 is A/D converted by an operational information encoding part 20 in a recording/reproducing device 30, and is encoded to a command code according to the value to be supplied to a system controller 11, and thus, the recording/ reproducing device 30 is remote controlled by an operation part 84 of a headphone 80.