The invention provides an exposure machine. A transparent protection cover encircling a light source lamp room and an illuminating lens group is arranged outside an exposure chamber, a space with clean indoor air for isolating external environment is provided for the light source lamp room and the illuminating lens group, and the transparent protection cover is connected and communicated with a first gas delivery pipeline. Gas is delivered into the transparent protection cover by the first gas delivery pipeline, so that the light source lamp room and the illuminating lens group are cooled, and the problem of atomization of an external lens of the exposure chamber as the light source lamp room and the illuminating lens group are cooled by directly extracting the clean indoor air in the prior art can be avoided, so that the light source lamp room and lenses of the illuminating lens group can be protected, an expensive high-pressure mercury lamp or lens can be saved, and the production cost is effectively lowered.