A hydrogen storage material is expressed by a composition formula, (Ca.sub.1-xA.sub.x).sub.1-z(Si.sub.1-yB.sub.y).sub.z, wherein "A" is at least one member selected from the group consisting of alkali metal elements, alkaline-earth metal elements, rare-earth elements, the elements of groups 3 through 6, Ni, Au, In, Tl, Sn, Fe, Co, Cu and Ag; "B" is at least one member selected from the group consisting of the elements of groups 7 through 17, rare-earth elements, Hf and Be; 0.ltoreq.x<1 by atomic ratio; 0.ltoreq.y<1 by atomic ratio; and 0.38.ltoreq.z.ltoreq.0.58 by atomic ratio. It is lightweight as well as less expensive. In principle, neither high-temperature nor high-pressure activation is required, because it exhibits a high initial activity. The operation temperature can be lowered and the hydrogen absorption content can be enlarged by controlling the kind and substitution proportion of the substituent elements appropriately.