PURPOSE: To obtain a molten metal-refining apparatus which enables to shorten a time for vacuum treatment without being influenced by the deformation of a ladle, by locating the ladle inside a tiltable and evacuatable vacuum vessel, and attachably providing a heating means.

CONSTITUTION: At first, a ladle 50 containing steel melt 10 in it is located at a ladle-setting position in a vacuum vessel 20, and an engaging part 51 is locked onto a pedestal 35 for supporting the ladle. A main vessel body 21 is then tilted by the motion of a not-illustrated hydraulic cylinder under the condition that it is supported at its trunnion shaft 41 by the bearing 43 of a truck 42, to remove slag from the steel melt 10. The truck 42 is then moved on a rail 49 to a refining position, and an inner cover 38 and an outer cover 23 are attached to the ladle 50 and the main vessel body 21, respectively. Heating is carried out by inserting electrodes 61aW61c from an upper part, an alloy is charged from an alloy hopper 103 through a shooter 101, agitation is carried out by injecting inert gas through a porous plug 55, and vacuum treatment is carried out by connecting the ventilating hole (ommited in the drawing) of the main vessel body 21 to a vacuum pump or the like.