To provide a device that keeps body posture in moving legs and a lower back, and allows three-dimensional muscle training of the legs and the lower back.

Struts 3 each having a predetermined length and each having a rod-like, columnar or tubular shape, or other shape are connected to predetermined parts of a footrest member 1 having the upper face to place feet. One side of an elastic tension member 4 having a predetermined length and flexibility, and made of a member having a string-like, belt-like, rope-like or pipe-like shape, or another shape is directly or indirectly installed to a predetermined part of the footrest member 1 or the strut 3. A foot hooking part 6 having a means onto which a toe is hooked is provided on the other side of the tension member 4. Direction change parts 5 each having a face extending in a predetermined direction for changing a tensile direction of the tension member 4 are provided in at least two predetermined parts on an upper side and a lower side of each strut 3, or in at least two predetermined parts of the footrest member 1 and an upper side of each strut 3.