An optical encoder light shielding plate has a plurality of bridge parts provided in parallel, each of the plurality of bridge parts having a metallic layer, and a slit formed between the plurality of bridge parts. The slit is configured to have light incident therefrom. In the metallic layer, a master-side surface on an exposed surface side of a conductive master body is arranged on a light incident direction side. The metallic layer is obtained such that a plurality of cavities are provided in parallel on the exposed surface of the conductive master body. A voltage is applied while the conductive master body is dipped in an electrolytic solution. The metallic layer is electrodeposited on the exposed surface of the conductive master body in the cavities.