To provide a passage blocking prevention method capable of preventing reduction and blocking of a passage due to adhesion of foreign matter, by effectively removing adhered foreign matter even when the foreign matter such as internal slug included in molten iron or oxide produced in an interior is adhered to the passage, in regard to heating molten iron by using a groove type induction heating apparatus having a groove type passage.

The passage blocking prevention method for the groove type induction heating apparatus is characterized by that when carrying out induction heating of molten iron stored in an iron storage furnace by the induction heating apparatus having the groove type passage 10, by passing solid material through the passage 10 along with the molten iron, the foreign matter adhered to the passage 10 is removed, and the passage is cleaned by carrying out reverse rotation in a direction of a flow of the molten iron flowing through the passage 10 during induction heating. Moving magnetic field generating electrodes generating moving magnetic fields are arranged along the passage 10, and it is preferable that the direction of the flow of molten iron is reversed by changing a moving direction of the moving magnetic fields generated by the moving magnetic field generating electrodes.