Abstract: A blue-emitting phosphor of europium-activated barium magnesium aluminate is used in a high color rendering three-band type fluorescent lamp, in which the particle size distribution is uniform to obtain excellent phosphor layer. A fluorescent lamp employing the blue-emitting phosphor mixed with red and green-emitting phosphors has a uniform emission luminance distribution and increased luminous flux intensity. The employed blue phosphor is expressed:Ba.sub.a Mg.sub.b Al.sub.c La.sub.x O.sub.a+b+3(c+x)/2 :Eu.sub.dwhere 0.1.ltoreq.a.ltoreq.2.4, 0.1.ltoreq.b.ltoreq.5, 8.ltoreq.c.ltoreq.64, 0.001.ltoreq.x.ltoreq.0.2, and 0.1.ltoreq.d.ltoreq.4.