The present invention is applied for an image capturing device having a light source and a camera that captures an image of a measurement subject placed in an optical path that lies between said camera itself and said light source. The image capturing device according to the present invention includes a control unit that subtracts a plurality of frame images captured by said camera during an OFF period of said light source from a plurality of frame images captured by said camera during an ON period of said light source, the number of frame images captured by said camera during the OFF period being the same as that number of frame images obtained by said camera during the ON period and integrates the differences between their images.