PURPOSE: To improve the encoding efficiency of a moving image.

CONSTITUTION: When the movement degree of the moving image is high, a DCT block A is outputted from a switching circuit 16 and when the degree is low, a DCT block C is outputted from the circuit. When the DCT block A is outputted, if the fluctuation in the vertical direction is large, the DCT block A is outputted from a DCT block constituting circuit 20 and if it is small, a DCT block B is outputted from it. Similarly, when the DCT block C is outputted, if the fluctuation in the vertical direction is large, the DCT block C is outputted from the circuit 20, and if it is small, the DCT block D is outputted from it. Thus, the optimum mode can be selected according to the local property of the moving image.