IRRADIATION DEVICE To provide an irradiation device capable of preventing myopia or slowing the progression of myopia by the action of light irradiated toward the eyeball. An irradiation device (10) comprises a light source (1) and an instrument (2) on which the light source (1) is mounted. The light source (1) emits at least light having a wavelength within a range of 350 to 400 nm, inclusive, and is disposed in a position that allows irradiation in an eyeball direction when the instrument (2) is mounted. Further, the light source (1) is disposed in a position 0 to 100 mm, inclusive, from a surface of the eyeball. At this time, an irradiance of the light having a wavelength within the range of 350 to 400 nm, inclusive, is 0.02 to 1.0 W/m2, inclusive, on the eyeball surface when the instrument (2) is worn. Selected drawing: Fig. 1
