An action teaching method is provided for teaching a robotic arm of a robotic arm system through a gesture teaching device. In a step (a), a touch condition of a user's finger is sensed by the touch sensing unit. In a step (b), a sensing result of the touch sensing unit is transmitted to an identification unit, so that a touch information is identified by the identification unit. In a step (c), the touch information is transmitted to a teaching unit, so that the teaching unit actuates a corresponding operation of the robotic arm system according to the touch information. In a step (d), an operating result of the robotic arm system is shown on a display unit, so that the user judges whether the operating result of the robotic arm system is successful through the display unit.