An alkaline storage battery has a negative electrode using a hydrogen-absorbing alloy represented by a general formula Ln1-xMgxNiyAz wherein Ln is at least one element selected from rare-earth elements including Y, Ca, Zr, and Ti, A is at least one element selected from Co, Fe, Mn, V, Cr, Nb, Al, Ga, Zn, Sn, Cu, Si, P and B, and 0.15≦x≦0.30, 0<z≦1.5, and 2.8≦y+z≦4.0 are satisfied. The hydrogen-absorbing alloy has a hexagonal system crystal structure or a rhombohedral system crystal structure as its main phase and has a subphase of line which average number of not less than 50 nm in thickness existing in the range of 10 μm×10 μm in the cross section of the main phase is 3 or less.