A water purification apparatus includes a bottomed cylindrical container tank, a lid member for fluid-tightly closing an upper opening of the container tank, an upper filter which forms an upper space between the lid member and itself, a lower filter which forms a lower space between a bottom plate of the container tank and itself, a water passage pipe which passes through the upper and lower filters and which establishes a communication between the upper and lower spaces, and an ion-exchange resin loaded in a space defined by the container tank, the upper and lower filters and the water passage pipe. The lid member has a water supply pipe for supplying water to the upper space, and an overflow pipe which connects to the water passage pipe. A water conveyance pipe for discharging the pure water in the container tank to outside is connected to the lower space.