Abstract: A pure water manufacturing apparatus for producing ultra pure water to be used in the electronic and medical industries. This apparatus comprises a pure water circulation system consisting of a pure water storage tank, a first heat exchanger arranged at the downstream side of the tank for thermally sterilizing pure water, a filter arranged at the downstream side of the first heat exchanger for removing dead bacteria, a pure water circulating means, and a second heat exchanger for cooling pure water disposed between the filter and a terminal device at which pure water is required. The ultrapure water is supplied to the terminal device from the downstream side of the filter through the second heat exchanger.