To provide a threaded connection improved in preventing looseness for a carbon electrode column and/or a graphite electrode column.

The threaded connection comprises an outer member made from ceramic and having an internal thread; an inner member made from ceramic and having an external thread; the internal thread and external thread having thread windings with a substantially uniform lead, roots and crests, and individual thread windings with a substantially V-shaped profile; at least one of the internal and external threads being formed with a wedge ramp at the root and, when the inner and outer members are screwed into each other, the crests of one of the members abut with the wedge ramps at the root of the other one of the members; and the internal and external threads being cylindrical threads or conical threads.