A frame memory stores a plurality of captured images. An image selection unit selects a reference image, which is a standard for composition, from images other than an image which is captured earliest and an image which is captured latest among the plurality of images stored in the frame memory and selects images to be combined with the reference image from a group of images which are captured earlier and later than the reference image among the plurality of images. A composition processing unit composes the images to be combined selected by the image selection unit with the reference image selected by the image selection unit to generate a composite image.