The machining apparatus includes: a cover including a side plate, a projecting portion disposed below the side plate, a rectangular shaped front opening, and a semicircular shaped planar opening; a first door body including a first drum disposed in a first side of a mating surface, a first abutting surface connected to the first drum, and a first top plate, and accommodated inside the cover by rotated about a first axis; and a second door body including a second drum disposed in the second side of the mating surface, a second abutting surface abut to the first abutting surface on the mating surface, and a second top plate, and accommodated inside the cover by rotated about a second axis.