To eliminate the problem of clogging with residue by a method wherein a torque transmitting body, connected to the rotating shaft of a rotary feeder in a discharging pipe in a residue discharging device extended downward from the bottom of a pyrolysis furnace through a connecting member, is provided while a residue discharging passage is formed in the connecting member.

Upon operating a pyrolysis device, organic wastes, such as waste plastic and the like, are charged into a pyrolysis furnace 1 to generate the pyrolysis of the wastes by heating the pyrolysis furnace 1 by a heating device and residue is accumulated on the bottom of the pyrolysis furnace 1. After finishing the pyrolysis, heating is stopped and an opening and closing means at the lower end of a discharging pipe 6 is opened. Next, a driving device is driven to scrape the residue on the bottom of the pyrolysis furnace by the rotation of a scraper 4 and transfer the residue downward through the discharging pipe 6 by the rotary feeder 7 of a residue discharging device 5. Then, the residue is received into a residue receiving unit through a residue discharging passage 28 formed in the connecting member 22, connecting the outer tubular body 21 of a torque transmitting body 10 to the rotary shaft 8 of the rotary feeder 7.