A wearable action assisting device includes an optional control unit for generating a first instruction signal for generating power depending on a biological potential signal in a drive source, an autonomic control unit for generating a second instruction signal for generating power depending on a phase of a task of the wearer in the drive source, a generation unit for generating a drive current of the drive source based on the first and second instruction signals, a display unit having a screen displaying thereon a coordinate axis corresponding to a strength of the power, a detection unit for detecting the coordinate of a designated position in the screen, and a setting unit for extracting parameters corresponding to the detected coordinate from a table defining a correspondence between a coordinate in the screen and parameters of the signal processing, and for setting the extracted parameters in the optional control unit.