To provide a contraction method for direct-tension power, capable of obtaining high contraction force with a flexible and simple mechanism, and direct-tension power therewith.

A constriction mechanism is constructed, by stretching strings between partitions. The plurality of mechanism, capable of contracting the distance between the partitions, by constructing the middle section of the string between the partitions of the constriction mechanism with an electromagnet, are jointed to form a chain structure. By controlling the amount of current supplied to the electromagnet and adjusting the attractive force of the electromagnet, the length of the chain structure can be made to contract.