We proposed a power assist control method, which allows people with hemiplegia (paralysis on one side of the body) use a cycling wheelchair. We assumed one disable leg as a mechanical linked leg. When a torque occurs in a joint of the link, we calculate the force of the edge of the link, and convert it into the torque which rotates the pedal. With this proposed control method, human can use the cycling wheelchair with one leg more comfortably than without it.