Passive dynamic walking is one of the walking modes for a biped robot. In this mode, each leg is driven by gravitational force and the walk continues as a series of inverted pendulums. Although it is an energy efficient walk mode, it is known as a highly conditionsensitive method. For this, we proposed a sole shape design that achieves stability of walking over a wide range of conditions such as inclination and surface of a road. This sole shape is designed to provide a recovery force by pressing onto a floor in cases where the body inclines too much. The stabilization effect is easily applicable to human shoes by simple attachments onto soles. By using this stabilization effect shoes, walking support, especially for elder persons not to turn over, is expected to be achieved naturally without any external power. We conducted preliminary experiments with elder persons using the shoes. As the result, it was shown that the most users felt ease to walk on flat floor and slight slopes.