A diluted chemical liquid production apparatus has a structure that has a platinum group metal carrying resin column, a membrane-type deaeration apparatus and a gas dissolving membrane apparatus, which are sequentially provided in a supply line of ultrapure water; and has a pH adjuster injection device and an oxidation-reduction potential adjuster injection device, which are provided between the platinum group metal carrying resin column and the membrane-type deaeration apparatus. An inert gas source is connected to a gaseous phase side of the membrane-type deaeration apparatus, and an inert gas source is also connected to the gaseous phase side of the gas dissolving membrane apparatus; and a discharge line communicates with the gas dissolving membrane apparatus. A pH meter and an ORP meter are provided in the discharge line. Such a diluted chemical liquid production apparatus can control a pH and an oxidation-reduction potential.