To provide a buoyancy power generation unit for obtaining further large energy, compared with a conventional power generation method by generating a buoyancy to rotate a generator by effectively using only an energy obtained from the nature instead of a conventional method of obtaining electric energy from fossil fuel.

A battery charger charged with a natural energy by solar power generation, wind power generation, hydraulic power generation or the like as device starting energy is used to electrify a heating material, whereby bubbles are generated in liquid to push up a bubble receiving tray by the buoyancy. The generator is operated by a buoyancy drive unit, and power generated thereby is converted to the energy to the heating material. This operation is repeated to raise the internal temperature of a heat-resisting water tank, and a steam turbine is rotated by steam generated thereby. The generator is operated by the rotational drive of the steam turbine. According to this, a power equal to thermal power generation or nuclear power generation is generated.