This invention is capable of providing a water purifying apparatus with a comparatively simple configuration that can be used easily.First, a usage state is adopted by operating the knob of the faucet. In doing so, the detection means detects the flow of the water. As a result, the control unit supplies electricity to the ultraviolet light generator based on the detection signal form the detection means, and ultraviolet light is emitted. The emitted ultraviolet light then irradiates water within the passage. Water sterilization can then be carried out as a result of doing this. The ultraviolet light generator only generates light when the faucet is in use. It is therefore possible to utilize the ultraviolet light generator for long periods of time and savings are made with respect to power consumption. Further, a curving part is formed in the passage, and the ultraviolet light generator is arranged in the vicinity of the curving part. The time for which the water is irradiated with ultraviolet rays from the ultraviolet light generator is therefore made long, and the water purification efficiency is improved.