SYSTEM FOR PRODUCING ULTRAPURE WATER AND METHOD FOR PRODUCING ULTRAPURE WATER

Provided is a system for producing ultrapure water, said system being provided with a pre-treatment system, a primary purification system, and a secondary purification system in the stated order, wherein: the primary/secondary pure water system is provided with an ion exchange device that treats boron-containing to-be-treated water using an ion-exchange resin; the ion exchange device has an accommodation part for filling in the ion-exchange resin, a supply part for supplying the to-be-treated water to the accommodation part, and a discharge part for discharging treated water from the accommodation part; and, in the accommodation part, a boron-selective ion-exchange resin fills the supply-part side, and an ion-exchange resin other than the boron-selective ion-exchange resin fills the discharge-part side. Such a system for producing ultrapure water and method for producing ultrapure water make it possible to stably obtain ultrapure water having a reduced concentration of boron without applying a TOC load to a subsystem.