PURPOSE: To prevent a foot, etc. from being held and clamped by attaching a pair of brackets close to the end part of a cleat on one end part of a footstep supporting frame, mounting horizontal guide rollers to the upper and lower parts of both the brackets to lay an endless belt over the rollers, and providing and endless belt-guiding plate.

CONSTITUTION: A cleat 4 is horizontally laid on the upper part 1b of a footstep supporting frame 1, and a pair of brackets 7 are provided close to one end part 4a of the cleat 4 to one end part 1c of the footstep supporting frame. A pair of guide rollers 8, 9 are horizontally mounted to the upper and lower parts of both the brackets 7 so that they can freely rotate. A riser-endless belt 10 is laid over the guide rollers 8, 9, and between them a nearly circular arc guide plate 11 is provided to guide the belt 10. When the cleat 4 adjacent to the belt is moved upward and a foot, etc. abut against the belt 10, the endless belt 10 is simultaneously moved, and thus holding or clamping of the foot, etc. can be prevented.