An image coding apparatus and an image coding method allow selecting, according to an image in a macroblock to be coded, a most appropriate intra prediction mode for controlling the amount of generated code. The image coding apparatus includes a block feature quantity calculator which calculates, based on pixel values of pixels in the current macroblock in an input image, statistical information of each of the pixel values; and an intra-prediction block size determiner which determines, based on the calculated statistical information, an intra-prediction block size according to a predetermined reference such that a larger intra-prediction block size is more likely to be selected when a degree of change in the pixel value corresponding to a predetermined direction in the current macroblock is smaller. A encoder which performs intra-prediction coding on the current macroblock, in units of the intra-prediction block having the determined size.