Disclosed is a calcium absorption enhancer which does not strain a human body or a domestic animal to be administered with a calcium compound, and can supply a calcium ion in a sustained manner in the stomach or the like of the human body or the domestic animal after the calcium compound is administered so that the absorption efficiency of calcium in the body can be increased. The calcium absorption enhancer comprises a water-soluble calcium particle capable of releasing a calcium ion in an aqueous solution in a sustained manner as an active ingredient.
