The present invention provides a hydrogen absorption alloy, which includes chemical composition represented by the general formula M1M2M3CaMgNiM4wherein 16 x (d - 1.870)/(d - r) ≤ v ≤ 16 x (d - 1.860)/(d - r); 1.6 ≤ w ≤ 3.2; 4.1 ≤ x ≤ 5.1; 3.2 ...

The present invention provides a hydrogen absorbing alloy containing as a principal phase at least one phase selected from the group consisting of a second phase having a rhombohedral crystal structure and a first phase having a crystal structure of a hexa...