PURPOSE: To surely detect synchronization of a multi-frame signal by detecting respectively a horizontal synchronizing signal and a vertical synchronizing signal of a frame adjustment signal.

CONSTITUTION: One multi-frame MFL consists of 8 sub-multi-frames SMF1-SMF8 and each of the sub-multi-frames SMF1-SMF8 consists of two frames respectively. A frame adjustment signal FAS in 8-bits is arranged to each of frames FLM1-FLM16 and its bit assignment is configurated in the unit of multi-frame MFL. The synchronization of one multi-frame MFL is detected by detecting a horizontal synchronizing signal and a vertical synchronizing signal.