1. An imaging device comprising: an imaging means for capturing an image of a subject and generating image data; a storing means for temporarily storing plural pieces of image data consecutively captured by the imaging means; a first synthesizing means for adding and synthesizing the plural pieces of image data stored in the storing unit to generate first image data; a second synthesizing means for synthesizing one of the plural pieces of image data with the first image data to generate second image data; and an outputting means for outputting the second image data generated by the second synthesizing means.