An ECU (1) includes a circuit board (10), a connector (20) fixed to the circuit board (10), and a resin portion (50) covering the circuit board (10) and the connector (20). The connector (20) includes a connector housing (21) having a terminal holding wall (22) that separates the internal space from the external space, and terminal fittings (41) extend through the terminal holding wall (22). The connector housing (21) includes a surrounding wall (27) disposed on the lateral surface of the terminal holding wall (22) to surround the terminal fittings (41). A potting material (28) is disposed inside the surrounding wall (27) and separates the terminal holding wall (22) from the resin portion (50). This can prevent a melted resin from entering a hood (24) through press fitting holes (23) at the time of forming the resin portion (50) by mold forming.