[Problem] To provide an elongating/contracting work machine that is able to reliably and easily affix a shaft unit. [Solution] The elongating/contracting work machine is provided with: a rotating drive unit a work unit a shaft unit that couples the rotating drive unit and the work unit, transmits rotary force to the work unit, and can elongate/contract and a slide holder. The shaft unit has a tube body that can elongate and contract, the tube body is provided with an outer tube and an inner tube that can move within the outer tube, the slide holder comprises a large diameter section affixed to the outer tube and a small diameter section into which the inner tube is inserted, two each of a first protrusion and second protrusion that oppose each other sandwiching a first slit are provided to the surface of the small diameter section sandwiching a second slit, a bolt having a knob at the end is inserted into the first protrusion and is screw-threaded to the second protrusion, the diameter of the small diameter section shrinks, affixing the inner tube when the bolt is tightened by means of the knob, and the diameter of the small diameter section expands, releasing the affixing of the inner tube when the bolt is loosened by means of the knob.Le problème décrit par la présente invention est de fournir une machine de travail dallongement/contraction, qui est apte à être fixée facilement et de manière fiable à une unité darbre. La solution selon linvention porte sur une machine de travail dallongement/contraction pourvue : dune unité dentraînement rotative dune unité de travail dune unité darbre qui relie lunité dentraînement rotative et lunité de travail, transmet une force rotative à lunité de travail, et peut sallonger/se contracter, et dun chariot support. Lunité darbre comporte un corps de tube qui peut sallonger et se contracter, le corps de tube étant pourvu dun tube externe et dun tube interne qui peuvent se déplacer à lintérieur du tube externe, le support coulis
