The present invention provides a method of effectively modifying starch so as to have an inhibitory effect on swelling and disintegration equivalent to that of chemically-linked starch, without using chemicals or a large amount of water. The method of modifying starch includes subjecting a powdery mixture containing starch and water-soluble hemicellulose at a ratio of 99.5:0.5 to 80:20 (weight ratio) to moist-heat treatment at 100 to 200°C.