A first engagement unit and a second engagement unit are formed to be engaged with each other at a divided portion formed in a substantially ring-shaped frame of a control valve filter. The first engagement unit includes a first inclination surface and a recessed portion. The second engagement unit includes a second inclination surface capable of coming into close contact with the first inclination surface and a projection portion engaged with the recessed portion. The recessed portion and the projection portion are engaged from the diameter direction of the frame, and the first inclination surface and the second inclination surface are in close contact with each other, whereby the first engagement unit and the second engagement unit are engaged with each there, and therefore, the recessed portion and the projection portion can be prevented from being deformed or damaged.