Provided is an imaging device including: a photoelectric conversion unit; a charge holding portion; a charge transfer unit that transfers charges from the photoelectric conversion unit to the charge holding portion; an output unit that outputs a signal based on transferred charges; a first acquisition unit that acquires first image data based on charges generated in the photoelectric conversion unit in a first exposure time period; a second acquisition unit that acquires second image data based on charges generated in the photoelectric conversion unit in a second exposure time period that is a sum of exposure time periods for charges transferred from the photoelectric conversion unit to the charge holding portion for multiple times by the charge transfer unit and is longer than the first exposure time period; and a compression unit that reduces a gradation value of the second image data to generate a third image data.