To provide a regeneration tank for a water softener, which includes a flow controller for controlling the pressure within the regeneration tank and is provided with a coupling part capable of protecting a part fastened to the water softener.

The regeneration tank for regenerating the water softener includes: a hollow case having an injection part which has an opening formed therein and through which a regeneration material is injected, an insertion part inserted into the water softener, and a storage part provided between the injection part and the insertion part to store the regeneration material; a cap which is inserted into the injection part, covers the opening, and can control the pressure within the case; and a flow controller installed within the insertion part to control the quantity of water flowing into the case. Because the inflow water quantity is controlled to be constant, the regeneration flow quantity, the regeneration time and the regeneration efficiency are maintained constant. Furthermore, the pressure within the regeneration tank is controlled, so that the regeneration tank is prevented from being damaged by the internal water pressure.