Abstract—A new attachment for a legged robot to help walking on snowfield is proposed. The device works like a snowshoe for human and prevents the robot from sinking in or slipping on the snow surface. Comparing to a bipedal human, a multi-legged robot has much larger numbers of legs and their ranges of movement are limited. For this reason, it was difficult to attach a large foot without making leg collision or stepping on an adjacent foot. To overcome these problems, this paper proposes an automatic retraction and expansion mechanism of wide snow-contacting framings which are passively operated by gravitation. Also, for the problem of stepping on an adjacent foot, we propose a passive downward-deflection mechanism which allows the lower shoe to smoothly exit from the upper shoe. The experiments to examine the performance of movement on some snowfields and the measurement of slip resistance force showed the effectiveness of our design. The proposed shoe does not rely on any external control logic. Therefore, it is easily attached to many existing legged robots.