A motor operated valve, 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 (24, 224) through which the inlet port and the outlet port communicate with each other; a valve element (34, 234) configured to open and close a valve section by moving away from and toward a valve seat formed at an open end of the valve hole (24, 224); a motor including a rotor for driving the valve element (34, 234) in opening and closing directions of the valve section; a shaft configured to rotate with the rotor, the shaft having a hollow space open at a leading end thereof and slidably supporting the valve element (34, 234) in an axial direction thereof, the valve element (34, 234) being partially inserted in the hollow space; a spring being disposed in the hollow space, the spring being configured to bias the valve element (34, 234) in a direction in which the valve element (34, 234) protrudes through a leading end opening of the shaft; a spring holder (65, 265) disposed in the hollow space and between the spring and the valve element (34, 234), the spring holder (65, 265) receiving the spring at one end thereof and coming in contact with an end of the valve element (34, 234) at the other end thereof; and a motion converting mechanism configured to convert rotational movement of the rotor into translational movement of the shaft in the axial direction thereof, wherein surfaces of the valve element (34, 234) and the spring holder (65, 265) coming in contact with each other are spherical surfaces, one of which being a convex spherical surface while the other of which being a concave spherical surface having a larger radius of curvature than the convex spherical surface, wherein a center of the spherical surface of the valve element (34, 234) is located on an axis of the valve element (34, 234), and wherein when the radius of curvature of the concave spherical surface is represented by R and the radius of curvature of the convex spherical surface is represented by r, R and r satisfy: 1.4 ⁢ r ≤ R ≤ 4 ⁢ r. 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 (24, 224) through which the inlet port and the outlet port communicate with each other; a valve element (34, 234) configured to open and close a valve section by moving away from and toward a valve seat formed at an open end of the valve hole (24, 224); a motor including a rotor for driving the valve element (34, 234) in opening and closing directions of the valve section; a shaft configured to rotate with the rotor, the shaft having a hollow space open at a leading end thereof and slidably supporting the valve element (34, 234) in an axial direction thereof, the valve element (34, 234) being partially inserted in the hollow space; a spring being disposed in the hollow space, the spring being configured to bias the valve element (34, 234) in a direction in which the valve element (34, 234) protrudes through a leading end opening of the shaft; a spring holder (65, 265) disposed in the hollow space and between the spring and the valve element (34, 234), the spring holder (65, 265) receiving the spring at one end thereof and coming in contact with an end of the valve element (34, 234) at the other end thereof; and a motion converting mechanism configured to convert rotational movement of the rotor into translational movement of the shaft in the axial direction thereof, wherein surfaces of the valve element (34, 234) and the spring holder (65, 265) coming in contact with each other are spherical surfaces, one of which being a convex spherical surface while the other of which being a concave spherical surface having a larger radius of curvature than the convex spherical surface, wherein a center of the spherical surface of the valve element (34, 234) is located on an axis of the valve element (34, 234), and wherein when the radius of curvature of the concave spherical surface is represented by R and the radius of curvature of the convex spherical surface is represented by r, R and r satisfy: 1.4 ⁢ r ≤ R ≤ 4 ⁢ r.