The Faraday rotator which is transparent over ultra-violet wavelength region has been developed. At the wavelength of a Kr F laser the Verdet constants of Si O₂, H₂O and Na Cl are larger than the typical value of a Faraday glass for a glass laser system. A new technique to generate a repetetive pulse train has been demonstrated as an application of the UV Faraday rotator on the Kr F laser technology. An edemo-beam pumped Kr F laser with an intrademo-cavity Faraday rotator has produced an output with alternative polarization whose period is equal to the cavity round trip time by the injection of a short pulse polarized beam. The output was separated into a couple of polarized pulse trains by an external polarizer, when the pulse duration of the injection pulse was shorter than the cavity round trip time of l2ns. The pulse separation was 24ns and the typical pulse durationwas 12ns.