To provide a cover of a processing machine having a reduced installation space and a temperature adjusting mechanism.

The roof of the cover for covering a precision processing machine or the like is tilted downward toward the front from an inlet of air from a temperature adjusting apparatus having a device for temperature adjustment. A ceiling plate horizontal to a floor surface with a plurality of small holes is arranged, temperature-controlled air is introduced into the inside of the cover through a space formed by the roof and the ceiling plate, and the inside of the cover is kept in a constant temperature state.