Abstract: A hydraulic dental cement composition which comprises a mixture of a dental cement powder having silicon oxide for its essential constituent and a setting agent powder having polyacrylic acid for its essential constituent is disclosed. This composition is of high compression strength due to the silicon dioxide contained therein, and its own pulverulence makes it excellent in workability because it has only to be kneaded with water to be placed into a useable form. Addition of zinc oxide or the like enhances the resistance to deterioration of the composition.