PURPOSE: To pump up water efficiently by disposing a cylindrical air filtering wall at the lower portion of a guide tube for blowing out uniformly air bubbles from the entire inner face of the tube and mixing the air bubbles with water so that a composite specific gravity of the mixture is made smaller to produce buoyancy.

CONSTITUTION: Air compressed to high pressure by an air compressor enters into an air chamber 3 through an compressed air inlet 1 of an air bubble type water pump, passes through a filter wall 4 having a lot of fine halls defined through it, and blows out into water in a form of fine air bubbles. At the instant, air bubbles out from the uppermost portion of the filter wall 4 reise along the inner wall of a guide tube 5 and air bubbles blowing out from under the uppermost portion rises through the inner side of the passage of the aforesaid are bubbles. As a result, when the height of the filter wall is equal to or longer than the radius of the guide tube, the air bubbles rise while making a uniform mixture with water quickly. Thus, the water pump produces a lot of fine air bubbles and mixes them with water uniformly for making a mixture of water and air bubbles so that a composite specific gravity of the mixture is smaller than that of water to produce buoyancy for permitting an efficient pumping of water.