NOVELTY - Inlet and vent pipes (9,10) are connected to intake and emission sides of air pump (15), to which hydrogen is supplied. Water collection path (4) provided above guide rail (3) has higher order pool (5) in bottom side. Drain water pipe (7) connected to pool, has shut-off valve (19) and generator (8) below which lower order pool (6) is placed. Surge tank (13) is fixed in drop start position of pipe (7).    USE - Buoyancy pumping type hydroelectricity generator in mountain area, city building.    ADVANTAGE - Since electricity generation is not dependent on river water and is sufficiently made in the height according to construction technique of current billing, restrictions from river ground and mountain area or not received. Installation is possible even in city building and therefore demand of future age is met. Extension of hydroelectricity is performed easily without destroying nature and natural environment. Aqueductus replenishment is sufficient without stopping running of generator, since sufficient water quantity is used.    DETAILED DESCRIPTION - A hydrogen gas holder (14) and injection tube (11) are connected to the pipe (10). A flexible opening-closing valve is attached to an inlet pipe (9) and an injection tube (11). An up-down type opening-closing valve (12) is attached to stainless steel bucket (1). A desorption opening-closing valve is attached to the bag-like balloon (2) made of high airtight material. The balloon is attached to the guide rail (3) and is tied to the bucker by a connector material (16).    DESCRIPTION OF DRAWING(S) - The figure shows side view of buoyancy pumping type hydroelectricity generator.    Stainless steel bucket (1)    Bag-like balloon (2)    Guide rail (3)    Water collection part (4)    Higher and lower order pools (5,6)    Water pipe (7)    Generator (8)    Inlet pipe (9)    Vent pipe (10)    Injection tube (11)    Opening-closing valve (12)    Surge tank (13)    Holder (14)    Air pump (15)    Connector material (16)