The control valve has a body; a supply port, an output port, and a discharge port; a first pressure-sensing device; the valve body having a first valve section surface that forms a first valve seat surface; a valve seat body having a second valve seat surface that forms the second valve section surface; a second pressure-sensing device; and a solenoid section. The first effective pressure-receiving area, the first pressure-receiving area on the inner side of a portion where the first valve seat surface and the first valve section surface are in contact with each other, and the second pressure-receiving area on the inner side of a portion where the second valve seat surface and the second valve section surface are in contact with each other are set to be substantially the same, and the second effective pressure-receiving area is set greater than the first effective pressure-receiving area.