A laser working machine comprising: a torch configured that laser light is radiated to a workpiece there through; a first body having one end portion (BP1OE) on which the torch is mounted and another end portion (BP1AE) provided at a position opposite to the one end portion (BP1OE) in a direction along a first optical path, the first body comprising a first optical system configured to guide the laser light to the torch along the first optical path; and a second body having: a second body end portion (BP2E) attachable and detachable to and from the another end portion (BP1AE) of the first body; and a second optical path optically connected to the first optical path, wherein the laser working machine has a first shielding plate being for shielding the first optical path and a second shielding plate being for shielding the second optical path, and characterized in that the laser working machine further comprises a first light transmissive plate having a first optical path hole through which the first optical path and the second optical path are connectable to each other; a second light transmissive plate having a second optical path hole through which the first optical path and the second optical path are connectable to each other; a first slot which is provided at the another end portion (BP1AE) of the first body and in which the first shielding plate and the first light transmissive plate are selectively insertable in a sealed manner, a second slot which is provided at the second body end portion (BP2E) of the second body and in which the second shielding plate and the second light transmissive plate are selectively insertable in a sealed manner, wherein one shielding plate that is either the first shielding plate or the second shielding plate comprises a ventilating duct through which gas is sent to a shielded space surrounded by the first shielding plate, the second shielding plate, the first body, and the second body, and wherein another shielding plate that is either the first shielding plate or the second shielding plate comprises a discharge duct through which the gas is discharged from the shielded space. a torch configured that laser light is radiated to a workpiece there through; a first body having one end portion (BP1OE) on which the torch is mounted and another end portion (BP1AE) provided at a position opposite to the one end portion (BP1OE) in a direction along a first optical path, the first body comprising a first optical system configured to guide the laser light to the torch along the first optical path; and a second body having: a second body end portion (BP2E) attachable and detachable to and from the another end portion (BP1AE) of the first body; and a second optical path optically connected to the first optical path, a second body end portion (BP2E) attachable and detachable to and from the another end portion (BP1AE) of the first body; and a second optical path optically connected to the first optical path, wherein the laser working machine has a first shielding plate being for shielding the first optical path and a second shielding plate being for shielding the second optical path, and characterized in that the laser working machine further comprises a first light transmissive plate having a first optical path hole through which the first optical path and the second optical path are connectable to each other; a second light transmissive plate having a second optical path hole through which the first optical path and the second optical path are connectable to each other; a first slot which is provided at the another end portion (BP1AE) of the first body and in which the first shielding plate and the first light transmissive plate are selectively insertable in a sealed manner, a second slot which is provided at the second body end portion (BP2E) of the second body and in which the second shielding plate and the second light transmissive plate are selectively insertable in a sealed manner, wherein one shielding plate that is either the first shielding plate or the second shielding plate comprises a ventilating duct through which gas is sent to a shielded space surrounded by the first shielding plate, the second shielding plate, the first body, and the second body, and wherein another shielding plate that is either the first shielding plate or the second shielding plate comprises a discharge duct through which the gas is discharged from the shielded space.