1. An image processing apparatus comprising: an imaging unit configured to acquire a plurality of photographed images by detecting radiation; a combined image generation unit configured to generate a combined image of at least a first photographed image and a second photographed image among the plurality of photographed images; and a setting unit configured to transition the second photographed image of the combined image to a misshooting state or a reshooting state in conjunction with designating a misshooting state or a reshooting state of the first photographed image, if misshooting or reshooting of the first photographed image of the combined image is designated.