Abstract: An electric three-way valve comprises: an input port, a plurality of output ports and a valve core which rotates in a sliding manner in the valve seat by a driving force of a motor unit, wherein the valve core selectively opens or closes the plurality of output ports, the motor unit is attached as a separated constituent to an outside of an upper end surface of a cylindrical casing introducing refrigerant, the valve core is driven by a gear unit which transmits the driving force of the motor unit and is disposed inside the cylindrical casing, the cylindrical casing includes one opening portion and a side wall with an apex portion, a housing which is fixed to a cylindrical wall portion of the apex portion and is equipped with the motor unit is uprightly formed in the other opening portion, and the housing is attached to the cylindrical casing.