An electric valve comprising: a valve body that includes a valve chamber and a valve port; a valve member that opens and closes the valve port; a supporting member that supports the valve member to be capable of advancing and retracting with respect to the valve port; a driving shaft that includes an external thread portion and is disposed in a direction of advancing and retracting the valve member; a rolling bearing that rotatably supports the driving shaft and is held by the supporting member; a planetary gear mechanism that is connected to the driving shaft; and an internal thread member with a cylindrical shape that is fixed to the valve member and into which the external thread portion is screwed, wherein the supporting member supports the internal thread member in a manner that restricts rotation of the internal thread member about an axis and allows movement of the internal thread member in a direction of the axis, wherein the supporting member includes a valve-member guide hole in which the valve member is disposed, characterized in that, the internal thread member includes a lateral hole that extends from an outer surface to an inner surface of the internal thread member, wherein an inner space of the internal thread member and the lateral hole of the internal thread member form a pressure equalizing passage that connects, in a valve-closing state where a first end of the valve member is in contact with a valve seat of the valve port, the valve port to a back-pressure chamber, which is a space next to a second end of the valve member in the valve-member guide hole, and wherein the external thread portion enters the internal thread member to a position where the external thread portion closes the lateral hole in a full-open state where the valve member is farthest from the valve seat. a valve body that includes a valve chamber and a valve port; a valve member that opens and closes the valve port; a supporting member that supports the valve member to be capable of advancing and retracting with respect to the valve port; a driving shaft that includes an external thread portion and is disposed in a direction of advancing and retracting the valve member; a rolling bearing that rotatably supports the driving shaft and is held by the supporting member; a planetary gear mechanism that is connected to the driving shaft; and an internal thread member with a cylindrical shape that is fixed to the valve member and into which the external thread portion is screwed, wherein the supporting member supports the internal thread member in a manner that restricts rotation of the internal thread member about an axis and allows movement of the internal thread member in a direction of the axis, wherein the supporting member includes a valve-member guide hole in which the valve member is disposed, characterized in that, the internal thread member includes a lateral hole that extends from an outer surface to an inner surface of the internal thread member, wherein an inner space of the internal thread member and the lateral hole of the internal thread member form a pressure equalizing passage that connects, in a valve-closing state where a first end of the valve member is in contact with a valve seat of the valve port, the valve port to a back-pressure chamber, which is a space next to a second end of the valve member in the valve-member guide hole, and wherein the external thread portion enters the internal thread member to a position where the external thread portion closes the lateral hole in a full-open state where the valve member is farthest from the valve seat.