To provide a driving force auxiliary mechanism of a reciprocating type carrying base capable of achieving reduction of a size of the drive device of the carrying base, avoiding increase of positioning errors and occurrence of vibration at the stroke end of the carrying base by backlash even when carrying out power transmission using gear mechanism such as rack-pinion, and preventing interference of the carrying base and a carried article with other devices by surely restoring the carrying base to an intermediate position without stopping it at the stroke end even when the drive device of the carrying base is faulty.

The driving force auxiliary mechanism of the reciprocating type carrying base includes a restoring force generating means 4 for acting a resisting force as a restoring force coinciding with a decelerating direction to the carrying base 1 during deceleration time when the carrying base 1 goes for the stroke end from the intermediate position to be the base point between both the stroke ends and acting an assistance force as a restoring force coinciding with an accelerating direction during acceleration time when the carrying base 1 goes for the intermediate position from the stroke end.