PURPOSE: To detect surely a synchronizing signal even if a compression code error is generated by the defect of the line state or the like, by discriminating that a prescribed number of "0" data of compression picture signal data is continuous.

CONSTITUTION: Compression signal data (picture signal data VDT and synchronizing signal EOL) and a clock signal CLK transmitted from the transmission side through a line LINE are inputted to a serial data buffer 1, and compression signal data is stored successively in accordance with the clock signal. Compression signal data is taken out from the output terminal of the buffer 1 by a controlling circuit 4 and binary encoded and is sent to a recording part (which is not shown in figure). When compression signal data taken out from the buffer 1 includes "0" data, the output of an AND gate 2A is applied to a counter circuit 3; and when the counter circuit 3 counts a prescribed number of continuous "0" data which is the pattern of the synchronizing signal EOL, the counter circuit 3 sends a synchronizing signal detection output CAR to the controlling circuit 4 to report that the synchronizing signal is detected.