An apparatus and method to preferentially select code quantity from DPCM path in a manner to satisfy the target code quantity thereby preventing deterioration of image quality. Code quantities obtained by a first compression system of quantizing an input image signal by quantization steps different from each other, or code quantities obtained by a second compression system which has compression factor and loss which are lower than those of the first compression system are added on an encoding system selection basis to calculate a total code quantity of equi-length unit. A calculated total code quantity and a target code quantity in the equi-length unit are compared to determine quantization step in the first compression system in accordance with the comparison result to select, on the encoding system selection basis, the first compression system or the second compression system of performing quantization by the determined quantization step.