PURPOSE: To obtain a flavor improver containing protamine, etc., readily improving flavor while suppressing astringency and bitterness of coffee, tea, beans, etc., reducing an amount of waste liquor in a manufacturing process, having extremely bettered production efficiency.

CONSTITUTION: A protamine, e.g. a monoprotamine such as arginine monoamino acid, a diprotamine such as arginine lysine histidine, a triprotamine such as arginine lysine histidine and/or its salt is optionally mixed with an antioxidant, salt, spice, pH adjustor, etc., made into a form such as aqueous solution, emulsion or powder to give the objective flavor improver.