To assist the rotation of ankle to easily and correctly exercise a golf swing by forming a calcaneus face, whose level is lower than a talus face and a metatarsus face parallel to and at the inside bottom face of the base via a gap.

At an inside bottom face 1 of a sole shaped base 7, which is placed at the front side when exercising a golf swing, a calcaneus face 5 level is bored via a gap 6, whose level is lower than a talus face 3 and a metatarsus face 4. Similarly, at an inside bottom face of the sole shaped base 7, which is placed at the rear side, a calcaneus face is bored via a mild gap. This allows a player to shift his/her weight from a foot at the back to a foot at the front during a down swing, to rotate his/her waist with the front foot as an axis during an impact, to support the rear foot during a top swing, and to extend the front foot when finishing.