A walk assistance device comprises a thigh unit configured to be arranged on a thigh of the user, a shank unit configured to be arranged on a shank of the user, a foot unit configured to be arranged on a foot of the user, a knee position joint unit configured to couple the thigh unit and the shank unit in a swingable manner, and an ankle position joint unit configured to couple the shank unit and the foot unit in a swingable manner. The shank unit comprises a first replaceable member and a second replaceable member that extend along the shank of the user, and a length of the shank unit is adjustable by replacing each of the first and second replaceable members with another one having a different length.