A fully automatic magnetic filter includes an apparatus barrel, magnetic rollers, scrapers, and a motor. The number of the magnetic rollers is four and corresponds to the number of the scrapers. The magnetic rollers are located in the apparatus barrel, and each includes an outer layer and an inner core. The outer layer is sleeved onto the inner core. The inner core has a magnetic region and a non-magnetic region. The outer layers of the magnetic rollers are driven and connected through a gear. The outer layer of one of the magnetic rollers is connected with the motor and driven by the motor. Each scraper corresponds to the outer layer of a corresponding one of the magnetic rollers. When the iron filings adsorbed on the outer layer are rotated to the non-magnetic region, the iron filings can be scraped off by the scrapers.