The present invention relates to an oxygen supply device for water quality improvement, comprising: a housing (15) configured such that water is introduced through an inlet (12) and discharged through an outlet a bubble generating portion (10) comprising a Venturi tube portion (30) coupled to the outlet of the housing (15) such that water is introduced through the housing by a pressure difference between the outside and the interior of a channel resulting from a flow of compressed air supplied, through a supply tube (11), to a channel part having a reduced channel diameter, the bubble generating portion (10) thereby mixing the introduced water and the flow of compressed air such that bubbles are generated and discharged a moving means (40) for moving the bubble generating portion (10) in the upward/downward direction while supporting the same and a frame (50) for supporting the moving means (40) while being partially submerged in seawater. The present invention is advantageous in that the upward/downward position of the bubble generating portion (10) can be adjusted conveniently maintenance of the bubble generating portion can be performed above the water surface in a very convenient manner the fact that supply of compressed air reduces the pressure by means of the Venturi action and allows inflow of seawater can substantially reduce installation costs and maintenance costs compared with the conventional manner of rotating an impeller by a motor the bubble generating portion can crush water particles in multiple steps such that nanosized bubbles are generated the bubbles can be maintained underwater for a long time such that the amount of dissolved oxygen can be increased substantially and organic materials in an aquafarming site can be decomposed so as to purify the same.La présente invention concerne un dispositif dalimentation en oxygène pour lamélioration de la qualité de leau, comprenant : un boîtier (15) configuré de telle sorte que de leau est introduite à tr
