To restrain the growth of skull at the tip lower part of a trough, to eliminate a large-scale removing work of the skull and to increase the operating time of equipment by always or intermittently jetting fluid toward the tip lower part of the trough, cooling the tip lower part of the trough and also blowing off the skull.

A fluid header 21 is arranged near the lower part of the trough tip 8a of the fixed trough and connected with fluid piping 23. A fluid nozzle 22 is disposed to the fluid header 21 toward the lower part of the fixed trough tip 8a. Necessary number of the fluid nozzle 22 is arranged according to the width of the fixed trough tip 8a. Molten metal spattered from a mold 2 is blown off by jectting the fluid from the fluid nozzle 22 before reaching the lower surface of the fixed trough tip 8a. As the fluid, it is desirable to use the compressed air. A skull detaching cutter is disposed near the lower surface of the fixed trough tip 8a and it is desirable to detach the skull stuck to the lower surface of the fixed trough tip 8a by advancing/retreating a skull detaching cutter with an actuator.