To provide a producing method of a reducing solution which is generated by mixing potassium carbonate, sodium hydrogen carbonate, L-cysteine hydrochloride, glycine, citric acid-hydrate and calcium chloride 2 hydrate, and by dissolving it into water; and which is capable of producing a large amount of reducing solution with low oxidation-reduction potential having sufficient reducibility for a long time just by a pure chemical reaction, without operating an auxiliary facility such as a hydrogen pressurizing device and the like, with only a simple work schedule, quite easily and whenever and wherever.

The reducing solution is generated after mixing 0.15-0.3 wt.% of potassium carbonate, 0.15-0.4 wt.% of sodium hydrogen carbonate, 0.8-1.2 wt.% of L-cysteine hydrochloride, 2.0-8.0 wt.% of glycine, 0.08-0.2 wt.% of citric acid-hydrate and 1.5-5.0 wt.% of calcium chloride 2 hydrate for 100 ml of water; and dissolving it into the water.