Abstract: Provided are a photography aid tool and a skin photographing device used for photographing skin. A main body is used for photographing skin with a portable device having a photographing device and an illumination device, and is composed of a front plate, a rear plate and a plurality of side plates. The main body has an insertion opening, a partition plate with two openings, and a portable device holder for holding the portable device. A polarizing filter is provided at the opening of the partition plate. The portable device is held by the portable device holder, and the skin photographing window of the front plate is in contact with the skin. The skin surface is photographed using only the light from the illumination device of the portable device while light outside the main body is blocked.