To provide a method and apparatus for production of ultrapure water for an immersion exposure system which prevent the occurrence of nano-size bubbles and roughness on a resist.

Ultrapure water treated by an ultrapure water production device and fed to a semiconductor manufacturing process as washing water is dispensed and passed through a degassing membrane to be degassed to a dissolved nitrogen of ≤3 mg/L, and a dissolved oxygen of ≤50 μg/L. The degassed ultrapure water is passed through an ion exchanger and an ultrafiltration membrane to remove ion components and fine particles in the ultrapure water.