The present invention relates to a microbial pesticide composition, which is obtained by a method including the steps of: adjusting a pH of a culture solution of the Bacillus sp. bacterium to from 3.0 to 5.0 (pH adjustment step)； mixing the culture solution with the calcium chloride and/or the magnesium sulfate (mixing step)； and lyophilizing or spray-drying the culture solution (drying step). In the microbial pesticide composition, even if it is stored for a long period of time at room temperature, the active ingredient remains stable and a sufficient preventive effect against plant disease can be maintained.
