The invention discloses a processing device with a processing head capable of performing reciprocating motion and preventing motion overtravel. The processing device comprises a rack (8) and the processing head (9) which is mounted on the rack (8), capable of performing reciprocating motion in the front-and-back direction, wherein a sliding groove cavity (90) which extends in the front-and-back direction is formed in the processing head (9); the sliding groove cavity (90) is in rolling cooperation with a roller pushing device, so that the roller pushing device pushes and pulls the sliding groove cavity to adjust the position of the sliding groove cavity in the left-right direction orthogonal to the front-and-back direction; and the roller pushing device comprises a threaded sleeve part (82) which is rotatably mounted on the rack (8) and is in thread fit with a threaded moving rod (83).