To provide an air conditioner outdoor unit water-cooled energy saving device securing uniform sprinkling of cooling water and eliminating the necessity of work of drawing the cooling water and control of water supply by a solenoid valve.

The air conditioner outdoor unit water-cooled energy saving device comprises: a water tank installed on a top plate of an air conditioner outdoor unit; a sprinkling mechanism comprising a net-shaped fiber product arranged on the air suction side of a heat radiation fin of the air conditioner outdoor unit and having excellent water absorbing property and diffusion; and a cooperation mechanism for taking in/out an upper end of the sprinkling mechanism to/from cooling water in the water tank in cooperation with the operation of an air conditioner. The cooling water is supplied from the water tank to the sprinkling mechanism by capillarity.