PURPOSE: To improve the coding efficiency.

CONSTITUTION: Picture data from a small block processing section 31 are given to an orthogonal transformation section 16 via a switch 33 and given to the orthogonal transformation section 16 via an inter-frame prediction section 32 and the switch 33. A comparison arithmetic section 36 compares a code quantity subject to in-frame compression with a code quantity of inter-frame compression in the unit of macro blocks and a coding mode selection section 37 decides the coding mode based on a history of the coding mode and the comparison result by the comparison arithmetic section 36 to control the switch 33. Thus, the coding efficiency is improved more than the case of deciding a macro block type in the unit of frames.