PURPOSE: To obtain a smooth photoconductive layer high in sensitivity, by continuously introducing hydrogen sulfide into a soln. containing cadmium ions, and adding a water-soluble indium compound after a prescribed time to form fine photoconductive cadmium sulfide powder having little roughness on the surface not causing agglomeration.

CONSTITUTION: Hydrogen sulfide is continuously introduced for a predetermined time into a soln. containing, e.g., CdSO4 until Cd2+ ions decrease to or below 1/3 of the initial concn., and then an ag. soln. of In2(SO4)3 is added, and introduction of H2S is continued for a prescribed time, and stopped. The resulting raw powder is washed with pure water, filtered, dried, and then heated to 450°C. The powder is dispersed into pure water and agitated together with cationic and anionic ion exchange resins, and agitation is continued until the electric conductivity drops to ≤1μΩ-1/cm, then separated and dried, thus permitting the obtained photoconductive CdS powder to have about 1μm average particle diameter, little reughness on the surface, excellent sensitivity and durability, and resolution capable of forming a sharp image.