PURPOSE: To provide a method for attaining external synchronization mutually among video cameras in the case of providing plural video cameras and switching them to be used.

CONSTITUTION: Independent television receivers (5-8) are provided in combination with the respective video cameras (1-4) provided in plural numbers and the signals of a same channel are received by the above-mentioned respective television receivers. The respective cameras separate sychronizing signals from video signals (S1-S4) in the same pertinent channel and mutual synchronization is coincided with the separated synchronizing signals as the external synchronizing signals of the respective video cameras.