There are provided a tablet-form immediate-release preparation that contains a high concentration of a casein and/or a casein hydrolysate as an active ingredient but has an excellent physical strength, a composition for the preparation that has an excellent tabletability, and a method for producing the preparation from the composition. Each of the preparation and the composition contains 50% by mass or more of the casein and/or the casein hydrolysate, and further contains a lactose having a volume average particle diameter of not less than 50 μm and not more than 300 μm. The content of the lactose is 6.0 to 100 parts by mass per 100 parts by mass of the casein and/or the casein hydrolysate. The method for producing the preparation contains the steps of: preparing a mixture as the composition； filling a mortar with the mixture and tableting the mixture； and separating the tableted mixture from the mortar.
