Agent for cooked rice

It is to provide a quality improving agent for cooked rice which effectively imparts improving effect on loosening properties, anti-aging property, and/or water retentivity to cooked rice with as little influence as possible on the original texture and taste of the cooked rice, a method for producing cooked rice using the quality improving agent, and cooked rice improved in loosening properties, anti-aging property, and/or water retentivity using the method for producing cooked rice. In the process of rice cooking for preparing cooked rice, substituted modified starch whose viscosity has been adjusted to a viscosity range involving a viscosity of 15 mPas or higher at 30% by mass in an aqueous solution and a viscosity of 3000 mPas or lower at 10% by mass in an aqueous solution by the hydrolysis or molecular weight reduction of the substituted modified starch is added as the quality improving agent for cooked rice. As a result, improving effect on loosening properties, anti-aging property, and/or water retentiv