A blue light-emitting phosphor emitting light with high efficiency by ultraviolet light of long wavelength as well as blue (to violet) light of short wavelength emitted from a semiconductor light-emitting element, particularly by the light having the wavelength in the range from 380 nm to 430 nm, is provided. A light-emitting device exhibiting high luminance and stable chromaticity is also provided by using the blue light-emitting phosphor. The blue light-emitting phosphor includes a divalent europium-activated or divalent europium- and manganese-activated aluminate phosphor, substantially represented by the general formula: a[(MI<SUB>1-c-d</SUB>Sr<SUB>c</SUB>Eu<SUB>d</SUB>)(Mg<SUB>1-e</SUB>M<SUB>e</SUB>)]O.bAl<SUB>2</SUB>O<SUB>3</SUB>, where MI represents at least one kind of element selected from Ca and Ba, and a, b, c, d and e are numbers satisfying 0.1<=a/b<=1.0, 0.2<=c<=0.8, 0.01<=d<=0.5, and 0<=e<=0.05. |