To provide a spare motive power device of a circulating cable way which includes a function for preventing the reverse rotation of a pulley without using a special reduction gear, and in which devices are compactly arranged.

The spare motive power device 23 includes: a spare driving unit 37 for generating a driving force; a driving transmission section 39 including a driving shaft 42 which rotates by being connected to the spare driving unit 37; and a link mechanism 15 to which the driving force is transmitted from the driving transmission section 39, and which transmits and blocks the driving force to/from an input shaft 27a of the reduction gear 27 linked to the pulley 19. A one-way clutch 45 is provided in the driving shaft 42 of the driving transmission section 39.