To obtain a linear motion operation device for a control member which has a simple structure with a low cost, and improves resolution of linear motion of the control member.

A linear motion operation device for a control member has a rotor 7 provided with a female screw 10 for operating linear motion of a control member 1, particularly a valve tappet 1 inside a gas or liquid conduction body 2. Rotation of the rotor 7 is transduced to linear motion of a screwed spindle 5 which can be engaged with the female screw 10 and is locked in its rotation. The rotor 7 is composed of a magnetized rotational body 8 interlocked with a current carrying stator 13 of a single strand. An angular position of the rotor 7 can be adjusted by means of the stator current. Preferably, screw pitch is comparatively rough, for instance, 30 degrees. A maximum rotational angle of the rotor 7 is less than 180 degrees.