A phototherapy device using excimer radiation in which, by skillful use of the individual peak wavelength of 308 nm and of the emission range of shorter wavelengths than 308 nm, the therapy effect is enhanced, and in which, at the same time, harm can be reduced is achieved using a XeCl excimer lamp and in which diseased sites of skin disorders are irradiated with UV-B radiation with an optical filter being used for changing the spectral shape of the UV-B radiation with which the diseased sites are irradiated.
