A motor operated valve comprising: a body (200, 220, 240, 260) including an inflow port (222, 262) through which fluid is introduced from an upstream side, an outflow port (224, 264) through which the fluid is delivered to a downstream side, and a passage through which the inflow port (222, 262) and the outflow port (224, 264) communicate with each other; a valve element to open and close a valve section provided on the passage; a motor including a rotor for driving the valve element in opening and closing directions of the valve section; a feed screw mechanism to convert rotational movement of the rotor into translational movement; and a stopper mechanism to restrict the translational movement of the rotor, wherein the feed screw mechanism includes: a guiding part mounted vertically on the body (200, 240), and including an external thread portion on an outer surface thereof; and a guided part (326, 325, 352) formed integrally with a cylindrical member, constituting a rotation shaft (326, 325, 352) of the rotor, including an internal thread portion on an inner surface thereof, and mounted around and thus supported by the guiding part, the internal thread portion being engaged with the external thread portion, characterized in that the stopper mechanism includes: a stopper portion (506, 820, 706, 348, 840) provided on the guided part (326, 325, 352); and a stopping face formed on the guiding part, when the valve element is driven by the motor to move in a valve opening direction, the stopping face stops the stopper portion (506, 820, 706, 348, 840) to restrict the movement of the rotor in the valve opening direction, the guided part (326, 325, 352) includes an enlarged-diameter portion (334, 335) at a position away from the internal thread portion, the enlarged-diameter portion (334, 335) is open toward the body (200, 220, 240, 260), and the stopping face is located on an inner side of the enlarged-diameter portion (334, 335) depending on a driving state of the rotor. a body (200, 220, 240, 260) including an inflow port (222, 262) through which fluid is introduced from an upstream side, an outflow port (224, 264) through which the fluid is delivered to a downstream side, and a passage through which the inflow port (222, 262) and the outflow port (224, 264) communicate with each other; a valve element to open and close a valve section provided on the passage; a motor including a rotor for driving the valve element in opening and closing directions of the valve section; a feed screw mechanism to convert rotational movement of the rotor into translational movement; and a stopper mechanism to restrict the translational movement of the rotor, wherein the feed screw mechanism includes: a guiding part mounted vertically on the body (200, 240), and including an external thread portion on an outer surface thereof; and a guided part (326, 325, 352) formed integrally with a cylindrical member, constituting a rotation shaft (326, 325, 352) of the rotor, including an internal thread portion on an inner surface thereof, and mounted around and thus supported by the guiding part, the internal thread portion being engaged with the external thread portion, a guiding part mounted vertically on the body (200, 240), and including an external thread portion on an outer surface thereof; and a guided part (326, 325, 352) formed integrally with a cylindrical member, constituting a rotation shaft (326, 325, 352) of the rotor, including an internal thread portion on an inner surface thereof, and mounted around and thus supported by the guiding part, the internal thread portion being engaged with the external thread portion, characterized in that the stopper mechanism includes: a stopper portion (506, 820, 706, 348, 840) provided on the guided part (326, 325, 352); and a stopping face formed on the guiding part, a stopper portion (506, 820, 706, 348, 840) provided on the guided part (326, 325, 352); and a stopping face formed on the guiding part, when the valve element is driven by the motor to move in a valve opening direction, the stopping face stops the stopper portion (506, 820, 706, 348, 840) to restrict the movement of the rotor in the valve opening direction, the guided part (326, 325, 352) includes an enlarged-diameter portion (334, 335) at a position away from the internal thread portion, the enlarged-diameter portion (334, 335) is open toward the body (200, 220, 240, 260), and the stopping face is located on an inner side of the enlarged-diameter portion (334, 335) depending on a driving state of the rotor.