To provide a garbage disposer capable of efficiently fermenting and decomposing even garbage containing an oil component or the like and composting the garbage.

The garbage disposer is provided with a fermentation vessel 10 with its inside partitioned into a plurality of treatment chambers, a transfer path 11 for sending the garbage from a treatment chamber 10A at one side to a treatment chamber 10B at the other side, a separation device 14 to remove fermentation-inhibiting substances such as the oil component from the garbage to be supplied to the fermentation vessel 10, and a hot-water vessel 20 for storing hot water to pour it on the garbage in the separation device 14. The separation device 14 has an outer body 25, a cylindrical screen basket 26 mounted inside the outer body 25, a rotary shaft 17 passing through the inside of the screen basket 26, and a rotor vane 30 fixed to the rotary shaft. The screen basket 26 is provided with a plurality of draining slits 33 in the screen basket 26, and the tip part of the rotor vane 30 is inserted into the respective draining slits. In the outer body 25, a draining hole 16 for discharging waste liquid passing through the plurality of the slits 33 outside is formed.