To provide a reciprocating device for a moving body which can reciprocate it at a high speed without practically decelerating after turning back even if a reciprocating range is short in the reciprocating device using a thrust generating mechanism such as a linear motor mechanism.

A reciprocating device reciprocates a moving body 2 by arranging a linear motor mechanism 1 in parallel to a reciprocating passage 11 of the moving body 2. A stroke means 4 is arranged in a turning-back part of the reciprocating passage 11, and stroke object parts 2c composed of an elastic material are arranged on both side surfaces of the moving body 2, and a speed detecting sensor 3 of the moving body 2 is arranged on this side of the turning- back part. A control part 5 is arranged to perform an operation on the stroke timing by the stroke means 4 from entering speed of the moving body 2 detected by the sensor 3 and an apparent distance by adding a deformation quantity of the stroke object parts 2c to a distance up to the turning-back part from the sensor 3.