A vacuum chamber of a flat display element manufacturing device comprising the upper side of an upper chamber with a convex profile is provided to prevent the upper chamber from being dropped in case that the inside of the chamber is formed in vacuum. An upper electrode(20) is positioned in the upper region of the inside of a chamber. A lower electrode(30) is positioned in the lower part of the upper electrode. The upper side of the upper chamber is compromised of the arch. The upper side of the upper chamber is made of the form which is over the time cross section consolation.
