To provide a garbage decomposition accelerating mixing mechanism capable of accelerating decomposition of garbage by microorganisms activated by mixing a large number of colonial bed materials with the garbage without allowing the implantation bed materials to stick together.

A rotary drum 3 having inside a large number of colonial bed materials 11 serving as a colony of microorganisms is rotated and a mesh 5 of a mesh circumferential wall 7 hooks the face of the colonial bed material 11 to generate rotary movement. Four triangular shaped colonial bed material face hooking translocation/mixing guide sections 9 having the mesh 5 located at the interval of 90 degrees and projecting inwards in the axial direction successively hook the colonial bed materials to make them rotate and get others over, thus, the colonial bed materials can be mixed with crushed garbage without sticking together.