In order to provide a walking assistance device that can avoid hampering the motion of the muscles of the user and will not move out of place inadvertently when worn by the user, principal engagement points of a support member for securely mounting an assisting force generator, which is disposed on a side of at least one joint of a lower limb to provide an assisting force to a movement of the lower limb, are provided at portions where a relatively small amount of movement of skin occurs when a trunk or joint is moved. In this way, the support member can be fastened firmly to the portions where an amount of movement of the skin is small and therefore it is possible to reduce the uncomfortable pressure caused during motion while preventing the support member from inadvertently moving out of place.