An image encoding method comprising encoding a current block of a current slice of an image, wherein: if the current block of the image is an initial block of the current slice of the image each of the following stops are performed: a step of determining whether the virtual block is completely identical to the current block or similar such that a maximum difference is equal to or less than a predetermined threshold value; and a step of determining, based on a result of the determining, an encoding mode from among a plurality of modes comprising a first mode, a second mode and a third mode, and a step of encoding the current block in the encoding mode, wherein the first mode is a skip mode for encoding information representing that the current block is encoded in the first mode, instead of encoding pixel values of the current block, wherein the encoding mode is determined as the first mode when the virtual block is determined to be completely identical to the current block or similar such that a maximum difference is equal to or less than a predetermined threshold value; wherein information about said predetermined values is separately encoded; and wherein: the second mode is a mode for encoding the first block based on discrete cosine transformation; and the third mode is a mode for encoding the first block based on a plurality of bit planes of pixel values. if the current block of the image is an initial block of the current slice of the image each of the following stops are performed: a step of determining whether the virtual block is completely identical to the current block or similar such that a maximum difference is equal to or less than a predetermined threshold value; and a step of determining, based on a result of the determining, an encoding mode from among a plurality of modes comprising a first mode, a second mode and a third mode, and a step of encoding the current block in the encoding mode, wherein the first mode is a skip mode for encoding information representing that the current block is encoded in the first mode, instead of encoding pixel values of the current block, wherein the encoding mode is determined as the first mode when the virtual block is determined to be completely identical to the current block or similar such that a maximum difference is equal to or less than a predetermined threshold value; wherein information about said predetermined values is separately encoded; and wherein: the second mode is a mode for encoding the first block based on discrete cosine transformation; and the third mode is a mode for encoding the first block based on a plurality of bit planes of pixel values. a step of determining whether the virtual block is completely identical to the current block or similar such that a maximum difference is equal to or less than a predetermined threshold value; and a step of determining, based on a result of the determining, an encoding mode from among a plurality of modes comprising a first mode, a second mode and a third mode, and a step of encoding the current block in the encoding mode, wherein the first mode is a skip mode for encoding information representing that the current block is encoded in the first mode, instead of encoding pixel values of the current block, wherein the encoding mode is determined as the first mode when the virtual block is determined to be completely identical to the current block or similar such that a maximum difference is equal to or less than a predetermined threshold value; wherein information about said predetermined values is separately encoded; and wherein: the second mode is a mode for encoding the first block based on discrete cosine transformation; and the third mode is a mode for encoding the first block based on a plurality of bit planes of pixel values. the second mode is a mode for encoding the first block based on discrete cosine transformation; and the third mode is a mode for encoding the first block based on a plurality of bit planes of pixel values.