To provide an organic photoelectric conversion element, imaging device, and optical sensor having low dark currents, and a method of manufacturing a photoelectric conversion element. Provided is a photoelectric conversion element, including: a first electrode; an organic photoelectric conversion layer disposed in a layer upper than the first electrode, the organic photoelectric conversion layer including one or two or more organic semiconductor materials; a buffer layer disposed in a layer upper than the organic photoelectric conversion layer, the buffer layer including an amorphous inorganic material and having an energy level of 7.7 to 8.0 eV and a difference in a HOMO energy level from the organic photoelectric conversion layer of 2 eV or more; and a second electrode disposed in a layer upper than the buffer layer.