PURPOSE: A novel storing and quality improving agent for a food, containing cinnamic acid and an organic acid as active constituents, and having improved storing effect with no toxicity to human bodies.

CONSTITUTION: Cinnamic acid is used in combination with an organic acid to give a storing and quality improving agent for a food. The use of the cinnamic acid with the organic acid produces the synergistic antimicrobial action, and exhibits remarkably improved antiseptic and antifungal effect compared with the simple use of the cinnamic acid. Cinnamic acid which is a natural product extracted from cinnamon or obtained by the synthetic method may be used as the cinnamic acid. An organic acid, e.g. acetic acid, citric acid or malic acid, usable for food other than the cinnamic acid may be cited as the organic acid. In adding the storing and quality improving agent to the food, the respective components are added in the form of a powdery mixture. Preferably, the amount of the agent based on the food is usually about 50W500ppm cinnamic acid and 50W5,000ppm organic acid.