To realize work having no uneven processing, and improve work efficiency.

A device movable along a surface is provided with at least two moving units 2AA and 2BB connected to each other by an extended/ contracted connecting means. Each moving unit is provided with at least one selective traveling unit for selectively setting a moving state for moving each moving unit in the extending/contracting direction of the connecting means or an unmoving state for inhibiting the movement thereof in the extending/ contracting direction of the connecting means. Each or at least one of the moving units is provided with work units 2A and 2B reciprocated in the direction crossing the extending/contracting direction of the connecting means. By setting one moving unit to the moving state and the other to the unmoving state and extending/contracting the connecting means, one moving unit is moved along the surface.