To provide a cover device for a processing apparatus having the effect superior in transmissivity, while improving strength of the cover device of the processing apparatus.

A transparent resin plate 10 composed of resin such as polycarbonate and a transparent glass pane 12 are joined via an adhesive resin layer 11 composed of an acrylic resin. The cover device superior in coolant resistance can be provided by minimizing an increase in the thickness of a transparent cover part 5, while largely strengthening strength of a transparent window part, by inserting punching metal 13 so as to be covered with this adhesive resin layer 11.