A novel ²-amylase having excellent practical applicability is found, and an object is to provide a practical use of the ²-amylase. Provided is a method for improving a food, which is characterized in that a ²-amylase derived from Bacillus flexus is acted on a food containing a polysaccharide or an oligosaccharide having an ±-1,4 bond of glucose as the main chain.