PURPOSE: To prevent theft by making a device not operate normally when it is stolen, and displaying differently from the time of a normal operation during inhibited processing, by detecting the presence of the cut-off of a power supply input, and detecting the presence of the coincidence of an identification code.

CONSTITUTION: In a case that 'vehicle+B power source' is disconnected, an operator displays previously a specified tuning frequency on a display 21, and it is required to give collate instruction from a control input part 19. When an inputted code F coincides with a previously inputted identification code F0, it comes into the normal operating state. But if not coincides, the trials of input of ten times portion are allowed, and if the input is not still performed correctly, the electronic circuit device is turned into an impossible state to use by turning it into a power supply off state, for instance.