To arrange a lighting means inside an actuator, and turn on the lighting fixture during maintenance or adjustment, thereby lighting work environment.

This positioner is provided with an angle detection means for detecting an operation opening of a valve, a control means for controlling the actuator for driving the valve based on an opening instruction signal supplied from the outside and the valve opening detected by the angle detection means, and the lighting means for lighting an adjustment and maintenance part such as a control substrate. The adjustment and maintenance part is lit by the lighting means during maintenance.