To prevent corrosion damage of an electric component of a displacement detection part (angle sensor), sticking of a rotary shaft, and the like.

In a positioner 100 in which an angle sensor 4 is fixed and installed to a control valve 200, and a control operation part 1, an electro-pneumatic conversion part 2 and a pneumatic pressure amplifier (pilot relay) 3 are housed in a case 5, a cable 6 for leading an electric signal from the angle sensor 4 to the control operation part 1 is provided with an air tube 62 for branching pneumatic pressure Ps to the electro-pneumatic conversion part 2 is branched to be guided into a detection part of the angle sensor 4. Thereby, the inside of the detection part of the angle sensor 4 is air-purged, and is maintained in a state free from rain water, humidity and the like.