PURPOSE: To prevent a camera from becoming a failure mode even when magnetic recorded information already recorded cannot be reproduced by recording a dummy signal when the information already recorded on a magnetic recording part cannot be reproduced and reproducing it.

CONSTITUTION: In the camera where a film F provided with the magnetic recording part by a track T is mounted and which executes the write and the read-out of the recording information by a magnetic head 5 while pressing the back surface of the film F by a press-bonding pad 6, the dummy signal is recorded on the track T when the recorded information already recorded on the magnetic recording part cannot be reproduced. Then, the failure diagnosis of the camera is executed by deciding whether the recorded dummy signal can be reproduced or not.