The purpose of the present invention is to provide a myopia treatment device. A myopia treatment device of the present invention comprises a light transmission part selected from a group consisting of an eyesight correcting tool, an eye protection tool, a face protection tool, a sunshade, a display device, a window, a wall, a light source covering, and a coating material. The light transmission part of the device transmits violet light having a wavelength within a range of 360 nm to 400 nm inclusive and thus treats myopia. Or, the myopia treatment device comprises a light emission part selected from a group consisting of lighting equipment, a display device, and a light irradiation device. The light emission part of the device emits violet light having a wavelength within a range of 360 nm to 400 nm inclusive and thus treats myopia.