Lower limb structure for legged robot, and legged robot

Provided is a lower limb structure for a legged robot with which a load on an actuator for driving a knee joint can be reduced. The lower limb structure for the legged robot comprises: a hip joint main body (18); a thigh portion (12a); a hip joint coupling (22) for connecting the thigh portion (12a) to the hip joint main body (18); and a knee joint main body (19) joined to the thigh portion (12a). The lower limb structure for the legged robot provides a thigh portion auxiliary link (31) having one end portion joined to the hip joint main body (18) or the hip joint coupling (22) to be rotatable about one pitch axis and the other end portion joined to the knee joint main body (19) to be rotatable about another pitch axis. A knee joint actuator (4) increases and decreases a length from the one end portion to the other end portion of the thigh portion auxiliary link (31).