A three dimensional printing apparatus including a base, a tank, a modeling platform, and a plurality of floating units is provided. A liquid forming material is filled in the tank. Each of the floating units connects between the base and the tank, such that the tank is disposed on the base in floating manner. The modeling platform is movably immersed in the liquid forming material. A three dimensional object is formed and adhered between the modeling platform and a bottom of the tank. The modeling platform drives and tilts the tank to move out of the base by the three dimensional object, such that the three dimensional object is released from the bottom of the tank by gravity.