PURPOSE: To improve the operating efficiency of a gate device by fitting a refractory plug formed with a hook-shaped through-passage into the cylindrical hole of a block attached to the bottom wall of a vessel for a molten metal and turning the plug to change over tapping passages.

CONSTITUTION: The circular conical cylindrical hole 6 is formed horizontally to the center of the refractory block 4 attached to the bottom wall of the vessel 1 for the molten metal. The refractory plug 8 of the circular conical shape formed with the through-passage 7 bent to a hook shape is freely turnably fitted into the hole 6. A communicating passage 9 for communicating the cylinder 6 with the tapping nozzle 3 of the vessel 1 is formed to the block 4. The plug 8 is turned to connect the one tapping passage 10a to the passage 9 through the passage 7 or to connect the other tapping passage 10b to the passage 9. The change-over of the tapping passages in plural directions is made possible by such mechanism, by which the smooth casting operation is accomplished.