PURPOSE: To eliminate need for a circuit to match the operation of a camera with an external synchronizing signal and for an interconnection cable by applying write/ read of image data to/from a memory based on a vertical synchronizing signal inputted by a synchronizing separator circuit from each camera and then outputting the resulting signal to a VTR.

CONSTITUTION: Each cable for video lines 1, 2, 3... from each of cameras A, B, C... is inputted to a switching device 5, which is switched for a prescribed time interval set by a switching signal from a control section 13 based on time information of a timer. Then video signals from the cameras A, B, C... are inputted to a synchronizing separator circuit 6, and a start signal generating circuit 12 inputs a synchronizing signal separated by the circuit 6. For example, the generating circuit 12 generates a start signal synchronized with a signal for a vertical blanking period of the synchronizing signal and outputs the start signal to an A/D converter 7, a memory 8, a D/A converter 9, and the control section 13 to allow the A/D converter 7 to convert its the control section 13 to allow the A/D converter 7 to convert its received video signal into a digital signal and to write and read out the digital signal to the memory 8 and to allow the D/A converter 9 to read the output of the memory 8 for its own starting.