In a strut bearing device, an upper spring seat made of steel has a cylindrical part and a disc part. The cylindrical part has, at an upper part thereof, an engagement hole penetrated in a radial direction. A lower case of a strut bearing has a cylindrical member fitted along an inner peripheral surface of the upper part of the cylindrical part. The cylindrical member has, at its outer peripheral surface, an engagement projection that is engaged with an engagement hole. Relative movement of the upper spring seat and the lower case in an axial direction and in a circumferential direction is restricted in a state where the engagement projection is engaged with the engagement hole.