Self-hardenable material

A self-hardenable material capable of forming a hardened product of the apatite type at a temperature in the vicinity of that of living body for use as a substitute or filler for the living body comprising calcium phosphate having a gram atom ratio of Ca/P of 1.3 to 2.0, a practically water-insoluble fluoride of an alkaline earth metal, an acid in an amount of 2 x 10-5 to 1.2 x 10-3 mol/g relative to calcium phosphate and water, the ratio of calcium phosphate to the practically water-insoluble fluoride of an alkaline earth metal being within the range corresponding to a gram atom ratio of Ca/F of 4.2 to 60 and the ratio by weight of powder component(s) to liquid component(s) being within the range of 10.0:2.0 to 10.0: 5.0.