The present invention relates to a power assist device or electric wheelchair that can facilitate people with disabilities arm movements More particularly, the plurality of the sensor unit that measures the amount of force, and a first communication unit for outputting the air and the resulting information from the sensor unit, and a plurality of power measurements that are installed at equal intervals on the wheel frame of the wheel chair module and, the one having a plurality of measurement modules and the connection connecting the handle dream Including and a second communication unit for receiving information from the first communication unit, the second control unit, which is installed on a part of the electric wheelchair by a control unit for controlling the motor of the electric wheelchair by receiving information from the communication unit but, in a state wherein the measuring module, the handle dream and the control unit is mounted on the electric wheelchair, the user manually applying a force holding the handle to rotate the wheels of the dream electric wheelchair, wherein in the sensor unit measuring the force applied to the handle Dream generates the information, the control unit is achieved by the power assist device characterized in that it controls the rotation speed of the wheel to control the motor in accordance with said information. Accordingly, because the existing measurement module can be easily installed only by screwing the wheel frame of the electric wheelchair can be easily mounted without changing the structure of the conventional electric wheelchair. In addition, the measuring module and control unit and for power supply by eliminating the signal wires are connected to the air, can be installed without a structural change of the conventional electric wheelchair, and has the advantage of maintaining a clean appearance. In addition, it is possible to install a power assist device for general electric wheelchair only screwed, there is also
