The present invention relates to a device for automatically sterilizing a food waste disposer which sterilizes the food waste disposer and effectively removes food waste remaining in the food waste disposer by allowing sterilization water to stay within the food waste disposer, and relates to a method for automatically sterilizing the food waste disposer using the device. As a device for automatically sterilizing a food waste disposer which is positioned between a sewer pipe (20) and a sink (S) including a drain port (10) into which food waste is injected, a device for automatically sterilizing a food waste disposer according to the present invention includes: a grinding part (100) which houses a grinding unit (110) to grind food waste injected into the grinding part, one side of which is connected to the drain port (10), and other side of which is connected to the sewer pipe (20) a sterilizing water generating part (200) which is positioned at one side of the grinding part (100), and which generates sterilizing water using raw water flown into the sterilizing water generating part a drain port cover (300) which opens or closes the drain port (10) between one side of the grinding part (100) and the drain port (10) and a sewer pipe cover (400) which opens or closes the sewer pipe (20) between other side of the grinding part (100) and the sewer pipe (20), wherein the sterilizing water generated in the sterilizing water generating part (200) is injected into the grinding part (100) to sterilize an inner part of the grinding part (100). A device for automatically sterilizing a food waste disposer according to the present invention is capable of solving hygienic problems such as malodor and others due to bacteria multiplication within the grinding part by allowing sterilizing water to stay within the grinding part for a predetermined time, thereby improving sterilization power and clearly removing food waste remained by being stuck to the inner part of the grinding part.
