An inter-field motion vector of an interlaced scanned inputted image is detected, and, using the detected inter-field motion vector, movements between fields are compensated to constitute a frame. The frame is then subjected to block coding. Alternatively, an interlaced scanned input image is subjected to two-dimensional block division and further an activity of each two-dimensional block is calculated. Using the activity as an index, the two-dimensional block is divided into either field small blocks constituted by field data or frame small blocks constituted by frame data, and the divided small blocks are coded. By these steps, even an image having large motion does not invite degradation of image quality, and high efficiency image coding can be realized.