An image pickup apparatus includes an irradiation unit for radiating, to an object, light having a plurality of wavelength regions, and an image pickup unit for picking up an image that is obtained when the light having the wavelength regions is radiated by the irradiation unit and an image that is obtained when the light is not radiated by the irradiation unit. Based on both images, a wavelength region from among the wavelength regions is determined in which the intensity of external light is low. The irradiation unit is then controlled to radiate light having an increased emission intensity for the light having the wavelength region in which the intensity of external light is low.