To provide a method and an apparatus for production of purified water for medicine which enable carrying out, efficiently in a short time, a treatment for production of purified water including a hot water sterilization process.

The method of producing purified water for medicine includes a hot water sterilization process as a start of the process of production of purified water and uses a reverse-osmosis membrane apparatus achieving a conductivity of permeated water of water to be treated at a water temperature of ≥60°C of ≤45 μS/cm. In the hot water sterilization process, return of concentrated water of the reverse-osmosis membrane apparatus and concentrated water, electrode water and desalted water of an electrical deionization apparatus to a raw water tank or their discharge out of the system is switched appropriately among a temperature-raising, a constant-temperature and a temperature-reducing process so as to carry out the hot water sterilization process efficiently. A production apparatus for the method is also provided.