1. An image processing device for generating a synthesized image from a plurality of continuous still images which are obtained by a continuous shooting, each of the plurality of continuous still images being associated with a piece of exposure information of a shooting, the image processing device comprising: an exposure correcting unit operable to correct exposures of still images used for generating the synthesized image, based on the exposure information and the number of the still images used for generating the synthesized image so that the synthesized image has an appropriate exposure; and a synthesizing unit operable to generate the synthesized image by synthesizing the still images whose exposures have been corrected by the exposure correcting unit.