Monitoring two-dimensional plasma uniformity in dry etching process by using the imaging plate has been investigated. It was found that the distribution of photostimulated-luminescence intensity of the imaging plate correlates well with the distribution of the ion density in the plasma measured with a Langmuir probe. The effect of ultraviolet light from the plasma has been investigated by covering the imaging plate with a quartz wafer. It was found that the imaging plate senses ultraviolet light from the plasma whose intensity is correlated with the ion density in the bulk plasma.