A wearable action-assist device which assists or executes an action of a wearer by substituting for the wearer is provided with an action-assist tool 2 having an actuator 201 which gives power to the wearer 1, a biosignal sensor 221 which detects a wearer's biosignal, a biosignal processing unit 3 which acquires from a biosignal “a” detected by the biosignal sensor a nerve transfer signal “b” for operating a wearer's muscular line skeletal system, and a myoelectricity signal “c” accompanied with a wearer's muscular line activity, an optional control unit 4 which generates a command signal “d” for causing the actuator 201 to generate power according to the wearer's intention using the nerve transfer signal “b” and the myoelectricity signal “c” acquired by the biosignal processing unit 3, and a driving current generating unit 5 which generates a current according to the nerve transfer signal b and a current according to the myoelectricity signal “c”, respectively, based on the command signal “d” generated by the optional control unit 4, and supplies the currents to the actuator 201.