PURPOSE:To enhance the fatigue characteristics by evaporating Se or an Se alloy and applying heat energy to the vapor or a vapor-deposited layer to form a photosensitive layer of Se contg. monoclinic system Se by a specified amount. CONSTITUTION:An Se or Se-Te alloy packed boat 3 is heated to 250-400 deg.C with a heater 4 to generate Se vapor or Se-Te vapor 6, and the vapor is heated to >= 1,000 deg.C with a heating element 7 such as tungsten wire sealed in a quartz tube between an electrically conductive support 1 and an evaporation source container 2. The heated vapor is then deposited on the substrate 1 to form a photosensitive layer of Se consisting of 10-40wt% monoclinic system Se crystals and the balance hexagonal system Se crystals. A vapor-deposited layer 10 formed by conventional system may be irradiated with electron beam 9 from an electron gun 8 moved back and forth in the arrow B direction while rotating the substrate 1 in the arrow A direction, thereby reducing the monoclinic system Se content of the layer 10 to said value. Thus, by converting monoclinic system cyclic Se with low positive hole mobility into hexagonal system chain molecules, the fatigue characteristics can be enhanced without deteriorating other characteristics.