The present invention provides a core particle for a pharmaceutical preparation which features the requisite properties of a core particle, and which has enough chemical stability, and in which reactivity with the drug (an active pharmaceutical ingredient) is limited or prevented. More specifically, the present invention relates to a core particle wherein a film containing an active pharmaceutical ingredient can be formed on the surface thereof, and (1) the core particle comprises a pharmaceutically acceptable inorganic material, (2) the inorganic material is poorly soluble in water, and (3) pH of a solution of the inorganic material is 5 to 8.