A swinging leg pendulum movement aid for walking (10, 58), comprising: a pair of assisting units for a left leg and a right leg, each of the assisting units including an auxiliary force transmission part having flexibility, characterized in that a first wearing part attached to one end of the auxiliary force transmission part and configured to be attached to a knee joint, wherein the first wearing part includes an upper winding part worn on a leg above the knee joint, a second wearing part attached to another end of the auxiliary force transmission part and configured to be worn on a lumbar area, and a drive source for applying a pulling force to the auxiliary force transmission part; a joint angle sensor (32, 54, 56) for detecting a joint angle of a front-back direction of the user's hip joints; a control means that detects from a detection value of the joint angle sensor (32, 54, 56) a state for which the leg that extended to the back when the user is walking has kicked off the ground and becomes a single leg standing state, implements drive control on the drive source, and applies the pulling force to the auxiliary force transmission part of the swinging leg that kicked off the ground so as to apply an assistance force in a forward swinging direction to aid a pendulum movement of the swinging leg; wherein the control means is configured to control the drive source so that the pulling force applied to the auxiliary force transmission part is cancelled when the control means detects from the detection value of the joint angle sensor (32, 54, 56) a state that the user is trying to extend the hip joint backward; and a memory means for storing control information relating to drive timing information and drive output information for driving each drive source with the left and right pair of assisting units corresponding to changes in the joint angle with the user's hip joints, wherein the control means is configured to do drive control of each drive source of the left and right pair of assisting units based on the control information of the memory means, wherein the memory means stores slack prevention control information to follow an effective length of the auxiliary force transmission part of the assisting unit corresponding to changes in the joint angle of the user's hip joints, and the control means is configured to do drive control of the respective drive sources of the left and right pair of assisting units so as to keep a fixed tensile force action state of the auxiliary force transmission part corresponding to changes in the joint angle based on the slack prevention control information stored in the memory means. a pair of assisting units for a left leg and a right leg, each of the assisting units including an auxiliary force transmission part having flexibility, characterized in that a first wearing part attached to one end of the auxiliary force transmission part and configured to be attached to a knee joint, wherein the first wearing part includes an upper winding part worn on a leg above the knee joint, a second wearing part attached to another end of the auxiliary force transmission part and configured to be worn on a lumbar area, and a drive source for applying a pulling force to the auxiliary force transmission part; a joint angle sensor (32, 54, 56) for detecting a joint angle of a front-back direction of the user's hip joints; a control means that detects from a detection value of the joint angle sensor (32, 54, 56) a state for which the leg that extended to the back when the user is walking has kicked off the ground and becomes a single leg standing state, implements drive control on the drive source, and applies the pulling force to the auxiliary force transmission part of the swinging leg that kicked off the ground so as to apply an assistance force in a forward swinging direction to aid a pendulum movement of the swinging leg; wherein the control means is configured to control the drive source so that the pulling force applied to the auxiliary force transmission part is cancelled when the control means detects from the detection value of the joint angle sensor (32, 54, 56) a state that the user is trying to extend the hip joint backward; and a memory means for storing control information relating to drive timing information and drive output information for driving each drive source with the left and right pair of assisting units corresponding to changes in the joint angle with the user's hip joints, wherein the control means is configured to do drive control of each drive source of the left and right pair of assisting units based on the control information of the memory means, wherein the memory means stores slack prevention control information to follow an effective length of the auxiliary force transmission part of the assisting unit corresponding to changes in the joint angle of the user's hip joints, and the control means is configured to do drive control of the respective drive sources of the left and right pair of assisting units so as to keep a fixed tensile force action state of the auxiliary force transmission part corresponding to changes in the joint angle based on the slack prevention control information stored in the memory means.