Abstract: A stool detergent releasing device comprises detergent releasing device installed within a water storage tank. The detergent releasing device being installed with a seat. The seat is communicable to the water storage tank. An upper interior of the seat is installed with a detergent container for receiving detergent; and a bottom of the seat has a ballcock. When the stool is flushed; the ballcock descends with the level of water in the water storage tank so that the detergent flows out from a bottom of the detergent container. When level of water in the water storage tank rises, the ballcock rises to resist against the bottom of the seat so as to stop the drainage of the detergent. Thus the detergent mixes with water in the water storage tank with a predetermined ratio.