Abstract: A feed device of a pyrolysis apparatus and a feed method through which material processed in the pyrolysis apparatus, such as plastic and/or rubber waste, can be fed into the pyrolysis apparatus. In the feed device there is a feed opening for the material to be processed, a feed chamber, closing members in conjunction with the feed chamber and a discharge opening, through which the material to be processed can be conveyed to the pyrolysis apparatus's pyrolysis chamber. A vacuum pump has been adjoined in conjunction with the feed device's feed chamber to achieve a vacuum or sufficient underpressure in the feed chamber after the material to be processed has been fed into the feed chamber and the feed chamber's closing members have been closed. After the closing member of the feed chamber's discharge opening has been opened, the material to be processed, from which the oxygen harmful to the pyrolysis process has been removed, is conveyed into the pyrolysis chamber.