A photosensitive drum protecting device for use in a color electrophotographic printer is provided. The printer, in which developing device cartridges of various colors including photosensitive drums and developing rollers are installed, and a printing path contacting the photosensitive drums is formed, includes a photosensitive drum protecting device that simultaneously exposes or protects each of the photosensitive drums. All of the photosensitive drums disposed at front end portions of the developing device cartridges are covered by just one photosensitive drum protecting device. Thus, the complexity of the printer is reduced and the printer can be made more compact.