To provide a method for manufacturing citric acid and calcium citrate efficiently and at a low cost by effectively utilizing an Ume (Japanese apricot) vinegar, and a shell of a scallop, or the like, an eggshell, or the like, which are conventionally discarded as wastes.

Calcium citrate is manufactured by the steps of carrying out desalination treatment of the Ume vinegar, then adding the powder of calcium carbonate or calcined calcium obtained from the scallop shell, the eggshell or a fossil coral into the treated Ume vinegar and mixing, and separating a formed precipitate. Further, citric acid is manufactured by the steps of adding sulfuric acid to the calcium citrate, separating and removing formed calcium sulfate, and concentrating and drying a residual aqueous solution.