<p>The ash melting furnace (1) disposes the combustion ash (A) resulted from incineration of municipal or other sorts of waste by melting it utilizing as the main fuel the unburnt carbon (C) contained in the ash itself. The ash melting furnace (3) includes a stationary plasma torch (1) which uses air for the working gas, and which is so placed facing the combustion ash (As) heaped up within the furnace (3) as to project its hot gas jet (B) thereon. The furnace (3) further includes a torch unit controller (2) that actuates the plasma torch (1) to secondarily heat and melt the ash (As). <IMAGE></p>