There is provided a support structure for a boss of a resin molded product. A plurality of cylindrical bosses stands up from one surface of a base plate to support a component. A plurality of reinforcing ribs extends radially from an outer circumferential surface of at least one of the bosses. The reinforcing ribs are arranged so as to be spaced apart from each other at a regular interval in a circumferential direction of the at least one of the bosses. Building-up portions are formed only on corner portions in which the outer circumferential surface of the at least one of the bosses and the reinforcing ribs intersect with each other.