A walking assistance device including a pelvic frame (10) extending from a lower back to each lateral side of a user, and a belly belt (20) for securing the pelvic frame in position. A power generator (30) is attached to each lateral side of the pelvic frame. A power transmitting arm (40) can be attached to an output member (33) of the power generator simply by hooking an upper part of a base end (41) of the power transmitting arm onto an upper groove (38) of the output member, and pushing a latch member or a slider (46) provided in a lower part of the base end onto a lower groove (39) of the output member. The user wearing the pelvic frame (10) can easily attach the power transmitting arm (40) to the output end of the power generator (30) by easily using a single hand without requiring help.