PURPOSE: To apply video recording check independently of a VTR to be connected by using a microcomputer to detect the presence of a serial code and applying a prescribed voltage to a terminal 3 as a video recording check when no serial code exists.

CONSTITUTION: A microcomputer 34 has a function generating a serial data and a function applying an H or L signal to discriminating circuits 32, 33 based on a serial clock from a VTR. The discriminating circuit 32 discriminates which of H, L is applied from the microcomputer 34 when a video recording check switch 31 is turned on and when L, the circuit 32 commands the generation of serial data to the microcomputer 34 and when H, the circuit 32 issues operating command to a prescribed voltage generatin circuit 55. Further, the discriminating circuit 33 discriminates the serial data from the microcomputer 34 and a prescribed voltage from the prescribed voltage generating circuit 35 in response to the H, L of the microcomputer 34 and transmits the result to the terminal 3.