<p>A structure for attaching a plasma gun to a chamber is provided with a chamber (2); a first engaging section (90) and a first positioning section (94) arranged on the chamber (2); a plasma gun (1) wherein a second engaging section (91) to be engaged with the first engaging section (90) and a second positioning section (95) to be positioned by the first positioning section (94) are formed on a flange (64); and a lock mechanism (3). The plasma gun (1) is attached to the chamber (2) by having the second engaging section (91) engaged with the first engaging section (90) of the chamber (2), the second positioning section (95) positioned by the first positioning section (94) of the chamber (2), and the flange (64) fixed by being pressed to a wall (80) of the chamber (2) by the lock mechanism (3).</p>
