This paper describes a new driving mechanism designed for electric wheelchairs that can move to all directions. The mechanism that was named ZMAC (ZMAC: Zero Moment Active Caster) includes differential gear, spar gears and two DC motors. One motor is for steering, and another is for driving the wheelchair. It was confirmed to be able to decrease the friction torque by this mechanism with steering motion of the wheelchair, by using the mechanism made for trial purposes. This paper also describes about disadvantage and future topics of ZMAC mechanism.