A walking assistance device deformable based on a thigh shape includes a hip joint actuator, an upper thigh frame connected to the hip joint actuator and configured to receive power from the hip joint actuator and rotate about a first axis and rotate about a second axis intersecting the first axis, a motion frame connected to the upper thigh frame, the motion frame including a plurality of segment frames configured to rotate relative to each other, and a lower thigh frame connected to the motion frame.