A lower extremity support tool (10) is provided with: right and left foot parts (11), the rear surface side of which facing the ground has a curved surface, and in which both feet of a user are individually placed on the surface side right and left leg parts (13) which connect to the foot parts of both feet and which extend along the vicinity of both legs of the user a waist part (14) which is in the vicinity of the waist of the user, supports the right and left leg parts so that same can individually rotate, and has right and left motors (15) for normally or reversely rotating the right and left leg parts and control units (16) which control the normal rotation or reverse rotation of the motors (15) on the waist part (14) so that, while the ground surface is held along the curved surface on the rear surface of one foot part, the other leg part that is on the opposite side of the leg part to which the aforementioned foot part is connected is rotated normally when the aforementioned other leg part begins to push off the ground, and the other leg part is reversely rotated when same is back to a starting position. As a consequence, it is possible to walk by means of a passive walking mechanism in which the ground surface is alternatively held by means of the rear surfaces (12) of the right and left foot parts (11) along the curved surfaces on the rear surfaces of the right and left foot parts (11).Linvention concerne un outil de support de membre inférieur (10) qui comprend : des parties pied droite et gauche (11), dont le côté surface arrière faisant face au sol a une surface incurvée, et dans lesquelles les deux pieds dun utilisateur sont placés individuellement sur le côté surface des parties jambe droite et gauche (13) qui sont reliées aux parties pied des deux pieds, et qui sétendent le long du voisinage des deux jambes de lutilisateur une partie taille (14) qui se trouve au voisinage de la taille de lutilisateur, porte les parties jambe droite et gauche de telle
