A method of producing a photoelectric conversion device having a multilayer structure formed on a substrate, the multilayer structure including a lower electrode, a photoelectric conversion layer made of a compound semiconductor layer, an n-type buffer layer made of a compound semiconductor layer, and a transparent conductive layer, is disclosed. A reaction solution, which is an aqueous solution containing an n-type dopant element, at least one of ammonia and an ammonium salt, and thiourea, is prepared, the n-type dopant is diffused into the photoelectric conversion layer by immersing the substrate including the photoelectric conversion layer in the reaction solution controlled to a temperature in the range from 20° C. to 45° C.; and the buffer layer is deposited on the photoelectric conversion layer by immersing the substrate including the photoelectric conversion layer subjected to the diffusion step in the reaction solution controlled to a temperature in the range from 70° C. to 95° C.