A machining apparatus , comprising: a cover including a side plate , a projecting portion connected to the side plate , the projecting portion disposed below the side plate , a front opening having a rectangular shape located on the side plate , and a planar opening having a semicircular shape located above the projecting portion , the planar opening connected to the front opening ; a first door body including a first drum disposed in a first side with respect to a mating surface , a first abutting surface connected to the first drum , and a first top plate connected to the first drum and the first abutting surface , the first door body configured to be accommodated inside the cover by rotating about a first axis that is offset toward a second side with respect to the mating surface ; and a second door body including a second drum disposed in the second side with respect to the mating surface , a second abutting surface connected to the second drum , the second abutting surface configured to abut to the first abutting surface on the mating surface , and a second top plate connected to the second drum and the second abutting surface , the second door body configured to be accommodated inside the cover by rotating about a second axis that is offset toward the first side with respect to the mating surface . a cover including a side plate , a projecting portion connected to the side plate , the projecting portion disposed below the side plate , a front opening having a rectangular shape located on the side plate , and a planar opening having a semicircular shape located above the projecting portion , the planar opening connected to the front opening ; a side plate , a projecting portion connected to the side plate , the projecting portion disposed below the side plate , a front opening having a rectangular shape located on the side plate , and a planar opening having a semicircular shape located above the projecting portion , the planar opening connected to the front opening ; a first door body including a first drum disposed in a first side with respect to a mating surface , a first abutting surface connected to the first drum , and a first top plate connected to the first drum and the first abutting surface , a first drum disposed in a first side with respect to a mating surface , a first abutting surface connected to the first drum , and a first top plate connected to the first drum and the first abutting surface , the first door body configured to be accommodated inside the cover by rotating about a first axis that is offset toward a second side with respect to the mating surface ; and a second door body including a second drum disposed in the second side with respect to the mating surface , a second abutting surface connected to the second drum , the second abutting surface configured to abut to the first abutting surface on the mating surface , and a second top plate connected to the second drum and the second abutting surface , a second drum disposed in the second side with respect to the mating surface , a second abutting surface connected to the second drum , the second abutting surface configured to abut to the first abutting surface on the mating surface , and a second top plate connected to the second drum and the second abutting surface , the second door body configured to be accommodated inside the cover by rotating about a second axis that is offset toward the first side with respect to the mating surface . <EOS>