An expansion valve for a vehicle air conditioning system, comprising: a body member where a first path and a second path that are separate from each other are formed; a movement member combined to be movable in a predetermined direction in the body member, one end of the movement member being exposed to the first path and receiving a pressure of the first path and another end opening/closing the second path; and an elastic member provided to elastically support the movement member in a direction of the first path, wherein as the movement member ascends or descends due to a difference between an internal pressure of the first path and an elastic force of the elastic member, the second path is closed or opened, wherein an orifice unit is formed on the second path, the body member comprises a cylinder unit communicated with the first path, and the movement member comprises: a piston unit received in the cylinder unit, an opening unit formed with a diameter that is greater than an interior diameter of the orifice unit to open/close the orifice unit, and a connection unit connecting the piston unit and the opening unit, characterized in that the expansion valve does not include a diaphragm so that the orifice unit may be opened and closed due to a difference from a resultant force of only a force generated when a pressure of the fluid moving through the first path is applied to the upper surface of the piston unit and the elastic force of the elastic member. a body member where a first path and a second path that are separate from each other are formed; a movement member combined to be movable in a predetermined direction in the body member, one end of the movement member being exposed to the first path and receiving a pressure of the first path and another end opening/closing the second path; and an elastic member provided to elastically support the movement member in a direction of the first path, wherein as the movement member ascends or descends due to a difference between an internal pressure of the first path and an elastic force of the elastic member, the second path is closed or opened, wherein an orifice unit is formed on the second path, the body member comprises a cylinder unit communicated with the first path, and the movement member comprises: a piston unit received in the cylinder unit, an opening unit formed with a diameter that is greater than an interior diameter of the orifice unit to open/close the orifice unit, and a connection unit connecting the piston unit and the opening unit, characterized in that the expansion valve does not include a diaphragm so that the orifice unit may be opened and closed due to a difference from a resultant force of only a force generated when a pressure of the fluid moving through the first path is applied to the upper surface of the piston unit and the elastic force of the elastic member. a piston unit received in the cylinder unit, an opening unit formed with a diameter that is greater than an interior diameter of the orifice unit to open/close the orifice unit, and a connection unit connecting the piston unit and the opening unit, characterized in that the expansion valve does not include a diaphragm so that the orifice unit may be opened and closed due to a difference from a resultant force of only a force generated when a pressure of the fluid moving through the first path is applied to the upper surface of the piston unit and the elastic force of the elastic member.