To provide a composition in which calcium-containing compound is stably preliminarily compressed and which is useful as a calcium source for patients suffering from osteoporosis or patients with a risk of having osteoporosis.

There is provided a preliminarily compressed composition which contains a calcium-containing compound and sugar alcohol in which the calcium-containing compound has a polycrystalline porous structure, and is selected from a group consisting of calcium carbonate, calcium citrate, calcium lactate, calcium phosphate containing tricalcium phosphate and dicalcium phosphate, calcium gluconate, bis-glycinocalcium, calcium citrate maleate, hydroxyapatite containing solvate, and mixture of them, one or more sugar alcohols are selected from xylitol, mannitol, maltitol, isomalt, and mixture of them, and a concentration of the calcium-containing compound is 60 wt.% or more. It is preferable that an administration form of the composition be a tablet, a capsule, a sachet, a chewing tablet or the like.