A shower head adapter includes a body part, which has one side connected to the inner circumferential surface of the inlet side of a main shower head body and the other side connected to a hose. The shower head adapter also includes a first circular groove formed along the outer circumferential surface thereof and a main body connecting part, which has an end on the other side protruding inwards from the inner circumferential surface thereof. A part of the inner circumferential surface is coupled to the outer circumferential surface of the inlet side of the main shower head body. A snap ring is inserted in the first circular groove. The diameter of the outer circumferential surface of the snap ring is larger than the diameter of the protruding inner circumferential surface of the main body connecting part.