PURPOSE: To prevent the erroneous lens loading by providing a loading display means on both a camera body and an exchange lens and raising an alarm to a user at the time of imperfect lens loading.

CONSTITUTION: An exchange lens 1 and a video camera 2 are freely attachable and detachable through mounts 3 and 4. A communication line is formed by an electric contact. When the regulate voltage is supplied to in a lens 1, a lens microcomputer is operated, the communication between the lens 1 and the camera 2 is started in synchronism with a clock to be sent from the camera 2, and a communication abnormality bit during the initial communication is read. In the case of no rising of communication abnormality bit, the normality of the lens mounting is informed by lighting up the light emitting element of a lens loading display 5 by turning on a transistor for the prescribed time. On the other hand, in the case the rising of communication abnormality flag, the abnormality of the lens loading is alarm-displayed by repeatedly turning on and off the transistor for the prescribed time and lighting up the light emitting element of the lens loading display 5.