The present invention has an excellent effect of providing method for mass culturing entomopathogenic nematodes using meal worm and vermiculite, and an environmentally friendly pest controlling agent against harmful insects by the granular formulation of entomopathogenic nematodes. A culture medium composition for mass culturing entomopathogenic nematodes is characterized by selecting any one among granule vermiculite having sizes 3-8 mm, 1-5 mm, and 0.3-1 mm.