To provide a linear driver for rapidly positioning a primary side or a secondary side of a linear motor at a central position with respect to a vibrating displacement of a movable unit at the time of starting driving, by detecting a relative positions of the primary and secondary sides and a movable limit by fewer number of sensors.

Two position sensors 3a, 3b are mounted at a distance of 1/2 vibration allowable range (d) at a primary side 18. Two members 2a, 2b to be detected are mounted in the range (d) at a secondary side 17. One end of the member 2a is made to coincide with a central position C with regard to a vibrating displacement of a trough 7, and its length is at least d/2 or more. The member 2b is mounted at a distance (d) from the one end which is made coinciding with the position C of the member 2a, and the length of the member 2b is d/2 or less. With such a constitution, the relative position of the primary and secondary sides and a movable limit can be detected by the two sensors, and a compact constitution of low cost can be made.