To obtain a still image with less image quality deterioration.

When the still mode is selected from the moving image mode, write to a frame memory 101 is inhibited, image data are stored and a switch 105 is thrown to the position of (b). The stored image data are subject to block processing, orthogonal transformation and delay as still image data and the result is given to an adder 109. A code quantity control circuit 11 controls a quantization step Si so as to be suitable for a recording rate. An identification level conversion circuit 110 revises an identification level of the quantization. The processing above is repeated while revising stepwise the identification level as to a still image of one frame and then quantization and variable length coding are conducted to obtain still image data coded by N-frames.