A three dimensional printing apparatus including a tank filled with liquid forming material, a platform disposed in the tank and immersed in the liquid forming material, and a curing tool disposed next to the tank is provided. The tank has at least two forming areas in step manner. The tank and the platform are controlled to generate a relative planer motion, wherein the platform moves from a forming area in higher step towards another forming area in lower step. When the platform moves to one of the forming areas, the curing tool cures the liquid forming material between the platform and the forming area to form a solidification layer on the platform. As the platform moves by at least two forming areas to form at least two solidification layers, the solidification layers are stacked to form a three dimensional object.