A manufacturing method of an optical member for optical path conversion to be connected to an optical waveguide provided in a substrate includes forming plural inclined surfaces on a wafer by etching, forming openings corresponding to the inclined surfaces in a plate-like member, forming a combined body, in which the inclined surfaces and the openings correspond to each other, by bonding the wafer and the plate-like member, and dividing the combined body into small pieces each of which includes the inclined surface and the opening.