The walking support device is mounted on a leg of a human body, and includes a walking support device (1) and a control unit (1) including a variable stiffness mechanism (4) whose rigidity with respect to a direction in which the knee bends and extends can be changed by driving a motor (42). 5). Based on the calculated relative speed, a toe movement calculating unit (53) that receives the output of the sensor (11, 21) that detects the movement of the leg and continuously calculates the relative speed of the toe with respect to the waist of the human body. A leg state determination unit (54) for determining which transition timing is between the swing phase and the stance phase. As described above, by using the relative foot tip speed with respect to the reference position of the human body, the transition timing between the swing phase and the stance period can be determined more accurately without using the pressure sensor of the sole.歩行支援装置は、人体の脚に装着され、膝を屈伸する方向に対する剛性がモータ(42)駆動を介して変更可能な可変剛性機構(4)を備えた歩行支援装具(1)と制御部(5)とを備えている。脚の動きを検出するセンサ(11,21)の出力を受け付けて人体の腰に対する足先の相対速度を連続的に算出する足先動き算出部(53)と、算出された相対速度に基づいて遊脚期と立脚期との間のいずれの移行タイミングかを判断する脚状態判断部(54)とを備えている。このように、人体の基準位置に対する相対的な足先速度を利用することで、遊脚期と立脚期間の移行タイミングを、足裏の圧力センサを用いることなく、より正確に判断する。