1. An image processing apparatus comprising: a conversion section that converts a moving object image which is an image in a region corresponding to a moving object included in a reference image and other images constituting a plurality of images generated under different exposure conditions so that the moving object image in the reference image corresponding to the moving object has the exposure levels of the other images so as to generate an exposure level converted moving object image for each of the other images; a substitution section that substitutes, via a processor, the generated exposure level converted moving object image with a region corresponding to an exposure level converted moving object image of each of the other images corresponding to an exposure level used as a reference exposure level at the time of generating the exposure level converted moving object image to generate a substitute image for each of the other images; a combination section that combines the substitute image generated for each of the other images and the reference image to generate a combined image; and a determination section that determines whether or not to generate the combined image based on an ISO sensitivity and an exposure difference of the plurality of images, wherein when the ISO sensitivity of the plurality of images is lower than a predetermined reference value and the exposure difference of the plurality of images is smaller than a predetermined reference value, the determination section determines that the combined image is to be generated.