An image coding apparatus comprising a coding unit generating coded data by executing prediction coding of an image of a coding target frame, a compression/decompression unit compressing a decoded image obtained by decoding the coded data and store it in a memory, and decompressing a compressed decoded image and output the decompressed decoded image as a reference image in the prediction coding, and a compression ratio calculation unit calculating a compression ratio of the compressed decoded image from the decoded image before compression and the compressed decoded image, wherein in accordance with the compression ratio of the compressed decoded image corresponding to a reference image used in inter-prediction coding processing among the stored compressed decoded images, execution of the bidirectional prediction using the reference image is controlled.