An organic waste processing method and device makes a mass disposal and 24 hours continuous processing possible, and can largely cut down facility and processing costs. It uses a number of roughly cut-end inverted cone shaped processing tanks 3, 3A, 3B, and 3C aligned serially, a motor 17 installed on the bottom of each processing tank, a rotating shaft 19 that rotates by motor 17 drive set up passing through the top and bottom parts inside each processing tank, and stirring blades 21, attached on rotating shaft 19, that mix aerobic microorganism 1 and organic waste 2 to put in more than capacity amount of organic waste 2 into the upstream processing tank 3, have a part of organic waste 2 transport from outlet 14 at upper peripheral wall of processing tank 3 to inlet 9 at the top of processing tank 3A placed adjacently and downstream, by centrifugal force of stirring blades 21. By repeating this process according to the number of processing tanks, a large amount of organic waste 2 is continuously aerobic fermented and turned into compost.