PURPOSE: To prepare soy sauce in a short time and in high utilization factor of nitrogen dissolution, capable of cooking a food ingredient without damaging its gloss, color and taste.

CONSTITUTION: Unrefined soy sauce after starting of preparation is kept at 20W 35°C for 6W20 days with stirring at times to give unrefined soy sauce at the early stage of preparation, from which 20% (v/v), preferably 30W50% (v/v) juice based on the total juice of the unrefined soy sauce is collected. The remaining unrefined soy sauce after collection of the juice is blended with 0.5W 1.5 as much solution of salt as the collected juice by volume (v/v), stirred fully, kept at 20W50°C temperature of the unrefined soy sauce for 1W3 weeks with stirring sometimes, and squeezed to give a filtrate. This filtrate is blended with the juice of the unrefined soy sauce.