In a system for transferring an analog video signal which contains command information and the like in vertical blanking interval VBI between master and slave devices via an analog line, information (bits 1 to 20) having a word configuration (words 0 to 2+CRCC) consisting of a predetermined number of bits (variable within the range from 5 bits to 80 bits) is superposed in a predetermined period (49.1 &mgr;s) of a predetermined VBI line (line number 10) at a predetermined clock (fsc/32 to fsc/2). In this manner, device which are interconnected via an analog video signal line can transfer information having various contents/lengths that can be changed in correspondence with a partner connected using vertical blanking interval VBI.