PURPOSE: To easily detect a position of a movable element by detecting sensor targets at front and rear parts of the element by a plurality of levitating direction displacement detecting sensors of a stator side, and selecting outputs from the front and rear sides in response to the advancing of the element.

CONSTITUTION: A front sensor target 4 is provided at a front part of a movable element 3, a rear sensor target 5 is provided at a rear part, and timing sensor targets 6, 7 are provided therebetween. A plurality of levitation and movable element position detecting sensors 1a-1h are provided at a predetermined interval along a rail at a stator 2. Output signals of the sensors 1a-1h are sequentially switched in response to the advancing direction position of the element 3, and the displacement of the element 3 is detected. At a position as shown, a sum signal of the outputs of the sensors 1e and 1b detects the target 4, a sum signal of the outputs of the sensors 1a and 1b detects the target 5, and the sensors are sequentially switched from the 1a toward the 1h. Thus, the position can be easily detected without special purposed sensors.