A walking aid device (10, 30, 40, 50) which aids a user's gait, characterized by: a drive part which includes a first tension adjusting part which adjusts tension of a first wire (10L, 33L, 34L) in which one end is fixed to a location corresponding to a left side of the user's lumbar region, a second tension adjusting part which adjusts tension of a second wire (10R, 33R, 34R) in which one end is fixed to a location corresponding to a right side of the user's lumbar region, and a frame which is erected relative to a walking surface and supports the first tension adjusting part and the second tension adjusting part so that they attain a mutually right-and-left paired relation at a position that is higher than the user's lumbar region, and applies external force independently via the first wire (10L, 33L, 34L) and the second wire (10R, 33R, 34R) while supporting each of the locations corresponding to the left side and the right side of the user's lumbar region; a gait recognition unit adapted to measure the user's stride, walking cycle, walking speed and centroid position during the user's walking motion and to recognize the user's gait; and a control unit adapted to set the user's ideal walking motion pattern by setting each of the user's pelvis inclination and rotation angle and speed thereof as optimal values, in which the time-oriented trunk balance is optimal, of the ideal walking motion pattern with the user's supported state as a reference based on a recognition result of the gait recognition unit, wherein the control unit further is adapted to drive the first tension adjusting part and the second tension adjusting part in synchronization with the walking motion pattern so that the user's overall pelvis swings alternately from side to side based on the walking direction to match changes in the time-orientated centroid position of the user's left leg and right leg, and the user's pelvis itself engages in three-dimensional inclination oscillation and rotation oscillation based on the user's trunk, and thereby respectively controls a level of increase/decrease of tension of the first wire (10L, 33L, 34L) and tension of the second wire (10R, 33R, 34R). a drive part which includes a first tension adjusting part which adjusts tension of a first wire (10L, 33L, 34L) in which one end is fixed to a location corresponding to a left side of the user's lumbar region, a second tension adjusting part which adjusts tension of a second wire (10R, 33R, 34R) in which one end is fixed to a location corresponding to a right side of the user's lumbar region, and a frame which is erected relative to a walking surface and supports the first tension adjusting part and the second tension adjusting part so that they attain a mutually right-and-left paired relation at a position that is higher than the user's lumbar region, and applies external force independently via the first wire (10L, 33L, 34L) and the second wire (10R, 33R, 34R) while supporting each of the locations corresponding to the left side and the right side of the user's lumbar region; a gait recognition unit adapted to measure the user's stride, walking cycle, walking speed and centroid position during the user's walking motion and to recognize the user's gait; and a control unit adapted to set the user's ideal walking motion pattern by setting each of the user's pelvis inclination and rotation angle and speed thereof as optimal values, in which the time-oriented trunk balance is optimal, of the ideal walking motion pattern with the user's supported state as a reference based on a recognition result of the gait recognition unit, wherein the control unit further is adapted to drive the first tension adjusting part and the second tension adjusting part in synchronization with the walking motion pattern so that the user's overall pelvis swings alternately from side to side based on the walking direction to match changes in the time-orientated centroid position of the user's left leg and right leg, and the user's pelvis itself engages in three-dimensional inclination oscillation and rotation oscillation based on the user's trunk, and thereby respectively controls a level of increase/decrease of tension of the first wire (10L, 33L, 34L) and tension of the second wire (10R, 33R, 34R).