PURPOSE: To operate a composite device as a specific device by not only setting one device to an operation mode but also releasing the operation mode of another device by a signal which is generated at an operation switching time.

CONSTITUTION: A composite device is formed by a record player, a cassette tape recorder and a radio receiver. Now, when SW1 corresponding to the player is turned on, a driving signal is generated from output part e through FF1 to operate the player, and the signal is applied to input part a of input switching circuit 4. Simultaneously, the output of FF1 is inputted to driving circuit 3, and input part a of circuit 4 is connected to output part d, and the composite device operates as the player. Next, for using the composite device as a tape recorder, when switch SW2 is turned on, the composite device operates as the recorder similarly, and an operation release signal is outputted from output part f by the output FF1 to release the operation of the player. Thus, the composite device can be operated as a specific device.