NOVELTY - A hydrogen-absorbing alloy powder has composition containing scandium, rare earth element containing yttrium, zirconium, hafnium and/or calcium, magnesium, nickel, and aluminum. The alloy powder has magnesium-rich nickel-poor region on the outermost surface and a magnesium-nickel-containing region in the inside. The magnesium-rich nickel-poor region contains magnesium at a larger molar ratio than the molar ratio of magnesium in the composition and contains nickel at a smaller molar ratio than the molar ratio of nickel in the composition.    USE - Hydrogen-absorbing alloy powder is used for negative electrode active material for negative electrode of nickel hydrogen secondary battery (all claimed). Uses include but are not limited to power supply for portable apparatus, electric tool, electric vehicle, hybrid type electric vehicles, digital camera, etc.    ADVANTAGE - The hydrogen-absorbing alloy powder provides nickel hydrogen secondary battery with excellent initial-stage characteristics activity, discharge capacity and cycle characteristics.    DETAILED DESCRIPTION - A hydrogen-absorbing alloy powder has compositional formula: R1-aMgaNibAlcMd, where R is scandium, rare earth element containing yttrium, zirconium, hafnium and/or calcium, M is element other than magnesium, nickel, aluminum and R, a is 0.005-0.4, preferably 0.01-0.15, b is 3-4.5, preferably 3-3.8, c is 0-0.5, preferably 0.05-0.5, d is 0-1, preferably 0-1, and b+c+d is 3-4.5, preferably 3-3.8. The alloy powder has magnesium-rich nickel-poor region on the outermost surface and a magnesium-nickel-containing region in the inside. The magnesium-rich nickel-poor region contains magnesium at a larger molar ratio than the molar ratio of magnesium in the composition and contains nickel at a smaller molar ratio than the molar ratio of nickel in the composition. The magnesium-nickel-containing region contains magnesium in a smaller molar ratio than the molar ratio of magnesium in the magnesium-rich nickel-poor region and contains nickel at a larger molar ratio than the molar ratio of nickel in the magnesium-rich nickel-poor region.