An image decoding method of decoding an image including a luminance component and a color difference component, the method comprising: acquiring transform coefficients; acquiring a reference image; selecting a first prediction mode or a second prediction mode based on a prediction mode that is explicitly or implicitly designated, the first prediction mode corresponding to a first prediction using a plurality of reference images, the second prediction mode corresponding to a second prediction using a single reference image; if the size of a block, which is a unit of an interpolation, is equal to or smaller than a predetermined first threshold value, and if the first prediction mode is selected for a color difference component, changing the first prediction mode selected for the color difference component to the second prediction mode, wherein the size of the block is determined by a width and a height of the block; generating a predicted image by performing, for each of the luminance component and the color difference component, an interpolation on the acquired reference image according to a motion vector by using the first prediction or the second prediction, wherein the generating step includes generating the predicted image for the color difference component without performing an interpolation using the first prediction when the size of the block is equal to or smaller than the predetermined first threshold value, and wherein the generating step includes generating the predicted image by performing the interpolation using the second prediction when the size of the block is equal to or smaller than the predetermined first threshold value, and generating a decoded image by adding the predicted image and a prediction error calculated from the transform coefficients. acquiring transform coefficients; acquiring a reference image; selecting a first prediction mode or a second prediction mode based on a prediction mode that is explicitly or implicitly designated, the first prediction mode corresponding to a first prediction using a plurality of reference images, the second prediction mode corresponding to a second prediction using a single reference image; if the size of a block, which is a unit of an interpolation, is equal to or smaller than a predetermined first threshold value, and if the first prediction mode is selected for a color difference component, changing the first prediction mode selected for the color difference component to the second prediction mode, wherein the size of the block is determined by a width and a height of the block; generating a predicted image by performing, for each of the luminance component and the color difference component, an interpolation on the acquired reference image according to a motion vector by using the first prediction or the second prediction, wherein the generating step includes generating the predicted image for the color difference component without performing an interpolation using the first prediction when the size of the block is equal to or smaller than the predetermined first threshold value, and wherein the generating step includes generating the predicted image by performing the interpolation using the second prediction when the size of the block is equal to or smaller than the predetermined first threshold value, and generating a decoded image by adding the predicted image and a prediction error calculated from the transform coefficients.