To provide cement mortar containing shell for resolving a problem about supplying difficulty of sand or ballast and difficulty of waste treatment of shells of oyster or scallop by using crushed shell as an aggregate of cement mortar.

In this cement mortar, crushed shell is used as an auxiliary aggregate. The surface of a block molded from cement mortar used the crushed shell as the aggregate is polished to obtain a concrete product wherein gloss specific to the shell is expressed on the surface. The shell is preferably used after crushing to about 2-10mm granular diameter.