A door mirror base including a base main unit for holding a vehicular door minor and a gasket disposed between the base main unit and a vehicle body. The gasket includes a hook protruding toward a vehicle body side and to be hooked onto the vehicle body. The base main unit includes a reinforcing pin passed through the gasket and protruding toward the vehicle body side of the gasket along the hook. The reinforcing pin includes a locking portion exposed on the vehicle body side of the gasket and caught by a surface of the gasket on the vehicle body side. By visually recognizing the locking portion from the vehicle body side of the gasket, it can be confirmed that the reinforcing pin is sufficiently passed through the gasket. Additionally, the locking portion makes it difficult for the reinforcing pin to be removed from the gasket.