A stable calcium preparation in solution form even at high concentration is provided. As such a calcium preparation, an aqueous preparation of calcium is provided, wherein the aqueous preparation of calcium includes, for example, water, calcium, a compound of Formula I, and a compound of Formula II as constituent elements, most of the calcium is in non-ionic calcium form and forms a complex, wherein in the complex, the calcium binds to the compound of Formula I and/or the compound of Formula II in a state that basic structures of these compounds are kept, at least a part of the complex forms colloidal particles, and the aqueous preparation of calcium is a transparent aqueous preparation having a pH equal to or higher than that of slightly acid； wherein, A 1 , A 2 , A 3 , A 4 , A 5 and A 6 are independently O - or OX, X represents a monovalent or polyvalent cation, and the Xs are the same or different when multiple OXs exist.
