To provide calcium carbonate which is water-soluble and easily ionized by decomposing protein solidifying the calcium carbonate of bone by adding balsam alcohol extracted liquid to the bone of squid.

The easily water-soluble calcium is provided by adding the balsam alcohol extracted liquid constituted by immersing 2-5 pts.wt. of entire balsam in 10 pts.wt. of ethanol contained aqueous solution having ≥10% ethanol and separating dregs, to the bone of squid. As the squid, golden cuttlefish, pacific flying squid, boad-mantle squid, swordtip squid and spear squid are used.