An actuator-equipped knee ankle foot orthosis comprising a thigh-side brace for being attached to a user's thigh; a lower leg-side brace for being attached to a user's lower leg, the lower leg-side brace being connected to the thigh-side brace so as to be rotatable around a user's knee joint; an actuator unit attached to the thigh-side brace and capable of imparting assisting force around the user's knee joint to the lower leg-side brace; a thigh orientation detecting means (510, 511, 515) capable of detecting an angle-related signal concerning a hip joint angle that is a forward and backward swing angle of the user's thigh at each of a plurality of sampling points that are set with predetermined interval in a gait cycle; and a control device configured to manage operational control for the actuator unit, wherein the gait cycle includes a heel contact phase including a heel contact time point when the user's heel contacts the ground in front of the user's body axis, a stance phase when the heel-contacted leg after heel contact is relatively moved backward while being in contact with the ground and a swing phase when the leg contacting the ground since the end of stance phase is raised and relatively moved forward, the actuator-equipped knee ankle foot orthosis being characterized in that the control device is configured to store an assisting force control data in advance that indicates a relationship between a thigh phase angle (φ) varying from 0 to 2π in the gait cycle and a size of gait assisting force to be imparted to the lower leg-side brace, calculate a thigh phase angle (φn(current)) at a sampling point (Sn) in a current gait cycle based on the angle-related signal detected by the thigh orientation detecting means (510, 511, 515) at the sampling point (Sn) in the current gait cycle, calculate a corrected phase angle (φn(ave)) obtained by correcting the thigh phase angle (φn) at the sampling point (Sn) in the current gait cycle using a thigh phase angle (φn(past)) at the corresponding sampling point (Sn) in a previous gait cycle that has already been completed, obtain an assisting force to be imparted to the lower leg-side brace by applying the corrected thigh phase angle (φn(ave)) to the assisting force control data, and control the actuator unit to output the assisting force, and the assisting force control data is configured such that the actuator unit outputs no assisting force at least in a period after an initial stage (X3a) of the swing phase in which the actuator unit outputs the assisting force for rotating the lower leg-side brace in a knee bending direction around the user's knee joint to raise the user's leg. the control device is configured to store an assisting force control data in advance that indicates a relationship between a thigh phase angle (φ) varying from 0 to 2π in the gait cycle and a size of gait assisting force to be imparted to the lower leg-side brace, calculate a thigh phase angle (φn(current)) at a sampling point (Sn) in a current gait cycle based on the angle-related signal detected by the thigh orientation detecting means (510, 511, 515) at the sampling point (Sn) in the current gait cycle, calculate a corrected phase angle (φn(ave)) obtained by correcting the thigh phase angle (φn) at the sampling point (Sn) in the current gait cycle using a thigh phase angle (φn(past)) at the corresponding sampling point (Sn) in a previous gait cycle that has already been completed, obtain an assisting force to be imparted to the lower leg-side brace by applying the corrected thigh phase angle (φn(ave)) to the assisting force control data, and control the actuator unit to output the assisting force, and the assisting force control data is configured such that the actuator unit outputs no assisting force at least in a period after an initial stage (X3a) of the swing phase in which the actuator unit outputs the assisting force for rotating the lower leg-side brace in a knee bending direction around the user's knee joint to raise the user's leg.