An imaging device includes an image data interface unit that outputs the first image data according to a pixel signal from a solid-state imaging device, an image data reading unit that reads image data from a storage unit and outputs the read image data as second image data, an image synthesizing unit that outputs third image data in which the first image data is synthesized with the second image data, an evaluation value generating unit that generates an evaluation value based on image data, a first image data selecting unit that inputs selected image data to the evaluation value generating unit, an image data writing unit that stores input image data in the storage unit via the data bus, a second image data selecting unit that inputs selected image data to the image data writing unit, and a display unit that displays an image corresponding to the third image data.