To enable the simple conversion of livestock feces such as cattle manure into an organic fertilizer, suppression of malodor from emitting during treatment and realization of the fertilizer formation in an early stage and simplify and compact the whole apparatus.

This apparatus for producing an organic fertilizer is obtained by diving and forming the interior of a treating casing 1 with partitioning wall part 18, 24, 34, etc., and successively arranging a mixing and preparing chamber 10 for suitability mixing livestock feces such as cattle manure with a moisture content regulating material, a pulverizing chamber 20 for regulating and controlling the conveying rate while pulverizing the resultant mixture after mixing, a heating chamber 30 for kneading the pulverized and mixed livestock feces, etc., B while compressing the feces and promoting the fermentation by heat generated with friction, a pulverizing and discharging chamber 50 for pulverizing the livestock feces, etc., B solidified after thermal kneading and bringing the pulverized faces into contact with air from the upper part. The apparatus further comprises ribbon screw type stirring shafts 13 installed in the mixing resulting chamber 10, pulverizing and feeding shaft units 21, having helical bladelike feeding blades 22 and separately arranged pulverizing pieces 23 and provided in the pulverizing chamber 20, a pressing shaft unit 31, having a helical bladelike feeding blade 32 and separately arranged pressing pieces 33 and installed in the heating chamber 30 and further a discharge shaft unit 51, having pulverizing discharging pieces 52 freely rotatably supported in the pulverizing and discharging chamber 50 communicating with the heating chamber 30 so at to enable the free opening and closing.