The effect of growth inhibitors on colonial growth of cellulolytic fungus, genus Trichoderma, was investigated to develop a method for the effective screening of various auxotrophs and hypercellulolytic strains. As the results, it was revealed that non-ionic detergents such as Sodium deoxycholate and Triton X-100 were the better ones as a growth inhibitor than Oxgall which has been used to restrict the colony size in genus Trichoderma. Each individual colony remained distinct on minimal plate supplemented with 0.05% Triton X-100 for as long as two or more weeks. The screening of 150 to 200 colonies simultaneous on a single plate was possible in the presence of Triton X-100. The effect of Triton X-100 on simultaneous screening was higher than that of Oxgall by a factor of two.