X-ray generation by a thermally heated LiNbO3 crystal and effect of ultraviolet (UV) laser light irradiation to a LiNbO3 crystal on pyroelectric electron emission were investigated. The x ray was detected with a gap distance of 15 mm between the surface of the crystal and the anode, whereas it was not detected with a gap distance of similar to 200 mu m. The dependence of the electron emission excited by UV laser irradiation on the vacuum pressure, laser power density, and gap distance between the crystal and the anode was measured. The electron emission showed a fast response with a rise time of 1 mu s to the laser irradiation. The emission current was 45 nA with a laser power density of 6.6 MW/cm(2) with a gap distance of 125 mu m between the surface of the crystal and the anode.