To provide an organic-matter treatment apparatus in which the strengths of a stirring rod are improved in the state of the stirring rod being mounted on a stirring shaft, and the stirring rod is made hard to break off.

In the organic matter treatment apparatus, a through hole 13a is formed in the stirring shaft 13 which is rotatively driven in a treating tank for treating organic matters such as garbage. One end 12a of the stirring rod 12 is passed through the through hole 13a and fixed. On the side of the one end 12a of the stirring rod 12, a small diameter part 12d is formed through a stepped part 12c from a large diameter part 12b of the stirring rod 12. In correspondence therewith, in the through hole 13a of the stirring shaft 13, a small diameter part 13d is formed through a stepped part 13c from a large diameter part 13b. At the same time, the clearance between the inside diameter of the through hole 13a of the stirring shaft 13 and the outside diameter of the stirring rod 12 placed inside the through hole 13a is constituted so that a clearance B between the small diameter parts 12d, 13d is made larger than a clearance A between the large diameter parts 12b, 13b.