An object of the present invention is to provide a garbage treating apparatus which has a fermenting reactor disposed upright with a vertical orientation and in which the garbage can be mixed with the compost without a circulation of the garbage between an interior portion of the fermenting reac tor and an outside portion of the fermenting reactor. Another object of the present invention is to provide a garbage treating apparatus wherein a continuous fermenta tion operation of the garbage can be carried out without a circulation of the garbage between an outlet of a fermenting reactor and an inlet of the fermenting reactor along a path outside of the fermenting reactor. A further object of the present invention is to provide a garbage treating apparatus wherein a garbage treatment operation from the start of crushing of the garbage to the end of cutoff of water supply to the garbage can be automated. According to the present invention. a garbage treating apparatus comprises a cylindrical fermenting reactor dis posed upright with a vertical orientation. and a garbage agitating means provided in the fermenting reactor. The garbage is introduced from a lower portion of the fermenting reactor and compost produced by a fermentation of the garbage is discharged from an upper portion of the ferment ing reactor. and the garbage is pushed up toward the upper portion of the fermenting reactor by agitating the garbage using the garbage agitating means. The garbage treating apparatus further comprises a means for generating a special kind of ?ow of the materials in the fermenting reactor so as to produce a mixing. This ?ow generating means generates a ?ow from the upper portion of the fermenting reactor to the lower portion of the fermenting reactor. when the garbage is pushed up from the lower portion of the fermenting reactor to the upper portion of the fermenting reactor using the garbage agitating means. One ?ow is formed ?om the lower portion of the fermenting reactor toward the upper portion of the fermenting reactor and another flow is formed from the upper portion of the fermenting reactor toward the lower portion of the ferment ing reactor within the fermenting reactor itself. The two ?ows are simultaneously generated in the fermenting reac tor. Thereby. it is possible to homogeneously mix the gar bage with the compost to a high degree. so that it is possible to easily dissolve the garbage. The heavy garbage may tend to drop down toward the bottom of the fermenting reactor due to gravity. however. according to the present invention. with the formation of the above stated two ?ows (an ascendant ?ow and a descendant ?ow) in the upper and lower directions. it is possible to homogeneously mix the heavy garbage with the light gar bage. Therefore. it is possible to uniformly proceed the fermentation treatment operation in the fermenting reactor