PURPOSE: To remove magneticaly attracted matters continuously, efficiently and surely, by providing a magnetically attracting rod freely protruding and retreating, to a flow-down zone in which mixed fuels are flowed down, and providing a scraping tool, etc. to remove said matters, attracted to the rod, to the outside of the zone.

CONSTITUTION: A magnetically attracting rod 7 is protruded into a flow-down zone of mixed fuels in a chamber 2 by actuating a hydraulic cylinder 10 to advance a rod 10a. In this state, the fuel is flowed down from a flow-out port 1a of a ball mill 1, and magnetically attractive matters such as iron powder contained in the fuel are attracted by a magnetic force of a permanent magnet 7a. When a large amount of said matters are attracted to the rod 7 by continuously flowing down the fuel in said state, the rod is retreated, while stopping a supplying of the fuel for a short time, after storing the fuel of surplus quantity. Thus, the attracted matters are scraped off by an attracted matter scraping tool 8, and fall into a hopper 5.