A component assembly includes a first component having a locking section and a flat-plate shaped projection formed on a first face. The locking section extends from the first face and bends in a first direction. The projection extends perpendicularly to the first face and is formed of a face intersecting the first direction. The assembly also includes a second component having a first hole and a second formed on a first face. The locking section of the first component is inserted into the first hole, and the projection of the first component is inserted into the second hole. The first face of the second component opposes the first face of the first component and includes a part with a slope section on which the distal end of the projection abuts and which moves the first component in the first direction when the first component is attached to the second component.