For the establishment of application technology for digestate from methane fermentation as the liquid fertilizer which is discharged in the process of livestock waste treatment, influence of fermentation load and fermentation period on Euglena gracilis proliferation was examined. Digestate from methane fermentation was pretreated in following steps: removed suspended solid from digestate by centrifugal separation, added buffer solution to digestate for controlling pH value around 5.5. Nine experimental plots were set and Euglena gracilis was nurtured in pretreated digestate for nine days. Euglena population was counted every three days. As a result, Euglena population increased in all examination plots more than in control plot (ordinary liquid fertilizer). We anticipated that the high fermentation load might be disincentive on Euglena population but it increased even in the highest fermentation load plot. In addition, the influence of the fermentation period on Euglena population was not significant. These findings indicate that digestate from methane fermentation can be used as the liquid fertilizer and we do not need to mind fermentation period. However, for nutriculture, it must be noted that the ammonia nitrogen account for nearly all of total nitrogen contained in digestate, and the amount of phosphorus is extremely small compared with that of nitrogen and potassium.