[PROBLEMS] To provide a quality-improving agent for cooked rice for improving the loosening properties of cooked rice and obtaining a cooked rice product with excellent qualities such as a soft and puffy texture and suppressed denaturation accompanying the aging of starch during preservation. To provide a processed cooked rice product having excellent qualities by using the same. [MEANS FOR SOLVING PROBLEMS] The loosening properties of cooked rice are improved by using, as the active ingredient, a water-soluble protein having been extracted and concentrated from pork, chicken, beef, fish, etc. and having a jelly strength of lower than 50 g. By combining this extract with water-soluble polysaccharides originating in soybean and using as a quality-improving agent for cooked rice, a processed cooked rice product having a soft and puffy texture and suffering from little denaturation in qualities during preservation can be obtained.