PURPOSE: To treat organic waste efficiently by a method in which organic waste is broken into small pieces, adjusted of its water content, mixed with fermentation fungi, pelletized, and fermented.

CONSTITUTION: In a container main body 2 placed slantingly and freely rotatably, a spiral guide part 25 is installed which is formed to advance in a different direction from that of the rotation of the main body 2. A mixture of organic waste broken into small pieces with fermentation fungi is fed in the main body 2, which is rotated so that the pieces of the waste are combined with each other to make pellets through the vertical movement by rotation. The pieces are heated by frictional heat generated by the rotation to be pelletized with drying. The outlet part 22 of the main body 2 is then opened by an operating means 7 to discharge the pellets by rotating the main body 2 in the opposite direction.