1. An image coding apparatus, which carries out coding of an inputted image, of a plurality of inputted images including one or more previous inputted images as reference images and a current image, by means of motion vector, comprising: a first detection unit, which is for detecting the motion vector by searching a predetermined search range in the inputted image based on macro block of transformation-inverse transformation-processed image; a second detection unit, which is for detecting a global motion vector between the inputted images based on a global macro block, larger than said macro block; a determination unit for search range, which can determine search range of the search by the first detection unit by means of the global motion vector detected by said second detection unit; a determination unit for utilization of global motion vector, which determines whether or not said global motion vector is utilized; and an acquisition unit for image size, which acquires image size of said inputted image, wherein said determination unit for utilization of global motion vector further comprises, a determination means dependent on image size, which carries out said determination based on the image size acquired by said acquisition unit for image size.