In this report,the optimum condition in injection control system of the solid manure injector,that is made as a trial by remodeling a manure spreader in previous report,is investigated on many experimental results. The tested material is bark manure. The volume of bark manure pushed to auger conveyer is adjusted by on-off control system on the electric circuit that moves the floor chain of a manure spreader,so that the fulling rate of auger filled with manure is able to keep the constant value of 80~90%. Under this condition, the injection volume of manure in farm can be arrenged easily by changing the revolution speed of auger shaft.