Research regarding Simplicillium lanosoniveum as an entomopathogen is still limited. The entomopathogenicity of Simplicillium lanosoniveum CG888 with three different conidia density treatments, namely 1x106/ml, 1x107/ml, and 1x108/ml, was tested on Callosobruchus maculatus F. imago in the laboratory, incubated at 26-27°C, RH 70% and in the dark conditions. Based on the effect of conidia density, S. lanosoniveum CG888 at a density of 1x108 conidia/ml caused greater mortality of C. maculatus F, reaching 51.65% compared to other treatments and control. The influence of the length of time after inoculation was that there was 60.83% C. maculatus F. death on the 11th day. It was higher than the result on 3, 5, 7 and 9 days later. There was a positive interaction that the mortality of C. maculatus F was influenced by the density of S. lanosoniveum CG888 conidia and the period of days after inoculation. Among these treatments, S. lanosoniveum CG888 with 1x108/ml caused mortality of 86,7% in C. maculatus on day 11 after inoculation. The lowest mortality of C. maculatus F. was in the density of 1x106 conidia/ml of 70%. These findings indicate that S. lanosoniveum CG888 can be used to control C. maculatus F. safely and reduce the use of chemicals in soybean storage.