To easily correct a deformed crucible to almost near the state before using by press-penetrating a punch having almost the max. diameter as the inner diameter of the crucible from the opening end pat while supporting the upper end or the lower end or both ends of the cylindrical water-cooling type crucible deformed with use.

In the case of lengthening the length of the crucible 2 by deforming with the use of the cylindrical water-cooling type copper crucible 2 in a consumable electrode type arc melting furnace, the lower end part of the crucible 2 is held with a holding tool 11 for correcting and punch 10 is press-penetrated from the opening end part to correct the crucible to the short length (pushing out method). In the case of extending the shrunk crucible 2, an upper end flange of the crucible 2 is held with a holding tool 12 for correcting, and the punch 10 is press-penetrated (drawing out method). In the case of unnecessitating the correction of the length, the upper part and the lower part of the crucible 2 are held with a holding tool 13 having the same length as the crucible 2, and the punch 10 is press-penetrated and the crucible 2 is corrected to near the state as the true circle in the vertical cross section thereof (both end fixing method).