PURPOSE: A plant growth promoting substance including white grub cast and a manufacturing method thereof are provided to prevent bad smell, hatred generation and economy deterioration. CONSTITUTION: A plant growth promoting substance includes white grub cast. The white grub is feed oak timer or Campanulaceae. The maggot cast is waste of the white grub which is feed oak timber or Campanulaceae. A manufacturing method of the plant growth promotion water comprises the following steps: breeding Maggot； and manufacturing the plant growth promotion water by mixing the cast of the maggot. The breeding step comprises the following steps: breeding the maggot by providing habitat of Scarabaeidae or Protaetia brevitarsis in the plant cultivation area； and giving bellflower and plant to feed the maggot.굼벵이 사육시 배설되는 굼벵이 분변토를 포함하는 식물 생장 촉진물 및 그 제조 방법이 기재된다.
