A motor operated valve driven by a stepping motor, comprising: a body having an inlet port through which fluid is introduced from an upstream side, an outlet port through which fluid is delivered to a downstream side, and a valve hole through which the inlet port and the outlet port communicate with each other; a valve element configured to open and close a valve section by moving away from and toward the valve hole; a stepping motor including a stator mounted on an end surface of the body, and a rotor configured to be rotated when power is supplied to the stator, for driving the valve element in opening and closing directions of the valve section; a shaft coaxially connected with the rotor, and configured to transmit a driving force of the stepping motor to the valve element; a stopper mechanism for restricting a rotation amount of the shaft; and a can fixed to the body, the can being a cylindrical member covering a space in which the valve element, the shaft, and the stopper mechanis are disposed and containing the rotor, the can defining an internal space in which a fluid pressure acts and an external space in which no fluid pressure acts, the can being coaxially inserted into the stator, wherein positions of the stator and the rotor in a rotating direction when the shaft is stopped by an operation of the stopper mechanism are set to be reference positions at which magnetic poles of the stator and magnetic poles of the rotor are opposite to each other, characterised in that the valve includes a fitting part (110, 112) formed on surfaces of the stator and the body attached to each other and the rotor is configured to be stopped at the reference position by an arrangement of the stopper mechanism, and wherein the stator is positioned relative to the body according to a positional relation between the fitting part (110, 112) and an insertion part where the can is inserted into the stator, and magnetic poles of the stator and magnetic poles of the rotor are opposite to each other at the reference positions. a body having an inlet port through which fluid is introduced from an upstream side, an outlet port through which fluid is delivered to a downstream side, and a valve hole through which the inlet port and the outlet port communicate with each other; a valve element configured to open and close a valve section by moving away from and toward the valve hole; a stepping motor including a stator mounted on an end surface of the body, and a rotor configured to be rotated when power is supplied to the stator, for driving the valve element in opening and closing directions of the valve section; a shaft coaxially connected with the rotor, and configured to transmit a driving force of the stepping motor to the valve element; a stopper mechanism for restricting a rotation amount of the shaft; and a can fixed to the body, the can being a cylindrical member covering a space in which the valve element, the shaft, and the stopper mechanis are disposed and containing the rotor, the can defining an internal space in which a fluid pressure acts and an external space in which no fluid pressure acts, the can being coaxially inserted into the stator, wherein positions of the stator and the rotor in a rotating direction when the shaft is stopped by an operation of the stopper mechanism are set to be reference positions at which magnetic poles of the stator and magnetic poles of the rotor are opposite to each other, characterised in that the valve includes a fitting part (110, 112) formed on surfaces of the stator and the body attached to each other and the rotor is configured to be stopped at the reference position by an arrangement of the stopper mechanism, and wherein the stator is positioned relative to the body according to a positional relation between the fitting part (110, 112) and an insertion part where the can is inserted into the stator, and magnetic poles of the stator and magnetic poles of the rotor are opposite to each other at the reference positions.