When image data having a size larger than a size transmittable in a predetermined format is to be transmitted, an image transmission apparatus divides the image data in a raster scanning direction in a unit of a predetermined number of pixels and sequentially allocates the image data of the unit of a predetermined number of pixels to a plurality of divided images in an order of the raster scanning direction to divide the image data into the plurality of divided images, and outputs the plurality of divided images through a plurality of transmission paths.