The present invention aims to provide a Eu-activated phosphor that maintains high wavelength conversion efficiency and suppresses deterioration with time due to vacuum ultraviolet irradiation, as well as a plasma display panel having superior display performance by suppressing sticking image caused by deterioration of the phosphor with time. To this end, the present invention provides a europium-activated phosphor where a divalent europium ratio of each phosphor particle constituting the phosphor is lower at and in a vicinity of a particle surface than for the particle as a whole. With such phosphor particles, it is possible to obtain the Eu-activated phosphor that has high maintaining ratio of emission intensity and high performance in suppressing deterioration with time in comparison with a conventional phosphor.