In an afterglow fluorescent lamp having a structure wherein at least a phosphorescent phosphor layer is set on the internal surface of a glass container, pinholes are prevented from appearing in the layer. The layer is formed, using a phosphorescent phosphor powder, wherein a metal oxide powder whose primary particles have a particle-size distribution with an upper limit particle size smaller than a lower limit particle size of a particle-size distribution that primary particles of a matrix material of the phosphorescent phosphor powder have is mixed, in a ratio by weight that is not less than 10 wt % but not greater than 40 wt %, with the matrix material of the phosphorescent phosphor powder. Therein, the particles of the metal oxide fill the gaps among the particles of the phosphorescent phosphor, and thereby the adhesive strength between the particles of the phosphorescent phosphor is heightened.