Abstract: A host fungus of a fungivorous nematode is inoculated on a solid medium or an artificial liquid medium containing an industrial vegetable waste or by-product, and then the nematode whose whole body have been sterilized is inoculated and mass-cultivated. Fungivorous ability of the nematode can be kept by subculturing using different host fungus on every culturing stage. The nematodes, when maintained about 10 days in an aerobic condition at 20-25.degree. C. with a relative humidity gradually inclined from high to low and dried to anhydrobiotic conditions, can be preserved for a long time. The nematode can be used for biological control of soil pathogens and soil insect pests.