We investigated the long-lasting photoluminescence (LLP) properties in a commercial zirconia powder with a monoclinic system after thermal treatment at different temperatures. Clear-blue photoluminescence and LLP were observed in the zirconia without emissive dopants subjected to thermal treatment at 1400 degrees C. Decay curve measurements revealed a pronounced, visually observable bluish LLP that lasted for similar to 10 h at moderate temperature. Based on spectroscopic observation and electron spin resonance results, a possible origin of the LLP is discussed.