A rotation angle sensor includes a housing, a detected object, a magnetism generation section, a housing cover, a circuit substrate, a sensing IC, and a resin body. The sensing IC includes a magnetism detection element, a molded body, and leads. The magnetism detection element outputs a signal in accordance with a change in a magnetic field due to a rotation of the detected object. The molded body covers the magnetism detection element. One end portion of each lead is electrically coupled with the magnetism detection element and the other end portion of each lead protrudes from the molded body and is electrically coupled with the circuit substrate. The resin body seals a portion of the molded body located between the magnetism detection element and the housing cover, the leads, and the circuit substrate.