Provided is a light irradiated toothbrush, in which light sources, irradiating light having mutually different wavelengths, are arranged in alternation at the bottom of waveguide bristles so that light of different wavelengths give rise to constructive interference which strengthens the intensity of the irradiated light, and the height of the light sources are varied on the basis of the wavelength of the light irradiated therefrom so as to effectively transmit light of short wavelengths to the waveguide bristles, and light having mutually different wavelengths are transmitted by means of the waveguide bristles, thereby effectively transmitting the light to the mouth of a user.