Abstract: Herein disclosed is a four-way valve for switching the cooling and heating modes of an air conditioner. The four-way valve includes: a first valve body of a cup shape having its closed wall formed with an outlet port and two circuit ports. A second valve body is provided having its root fitted fixedly on the first valve body and an inlet port formed at the side opposite to the body root. A cylindrical valve member is fitted rotatably in the first valve body having its one half formed in its end portion with an arcuate groove for providing alternate communication between the outlet port and the circuit ports and its other half formed with two communication ports. A member is provided for restricting the rotations of the cylindrical valve member. A magnetic member is provided for magnetically rotating the valve member when energized. A collar is disposed on the valve member and made irrotational but movable in the axial direction.