1. An image pickup apparatus comprising: a picture-taking section to continuously take pictures of a subject to output a plurality of image frames; an image synthesizing section to synthesize the plurality of image frames to produce a synthesized image; an image brightness adjusting section which allows the image synthesizing section to synthesize the image frames and executes image brightness adjusting processing for adjusting brightness of the synthesized image in continuous shooting by the picture-taking section; and a halfway-image display section to display an image which is being synthesized by the image synthesizing section in the image brightness adjusting processing.