To restrain looseness of a belt as much as possible by inserting the belt into a groove part penetrating in the diameter direction of a winding shaft, and movably arranging a belt looseness preventive member on the belt.

An adjusting belt 15 is set so that the tip can slip out to the other groove part 42 from one groove part 42 of a winding shaft 40. A belt looseness preventive member 17 is movably arranged to the adjusting belt 15 in a condition of sandwiching the adjusting belt 15, and is composed of a copper wire bent in a rectangular shape and a cylindrical pin inserted into the copper wire. When a first leg member being a handle is repeatedly reciprocated in the clockwise and anticlockwise directions to a leg member, the winding shaft 40 intermittently rotates in the anticlockwise direction together with a latchet, and the adjusting belt 15 is wound round the winding shaft 40. In this case, the pin of the belt looseness preventive member 17 is sandwiched between it and the adjusting belt 15 wound in the vicinity of the groove part 42 of the winding shaft 40, and the adjusting belt 15 is pressed down and fixed by the pin between it and the winding shaft 40 in an inlet part of the groove part 42, and becomes hard to slip out.