The objective of this research was to determine the pathogenicity of Nomuraea rileyi on larvae of Spodoptera litura. The isolate was from the infected Crocidolomia binotalis. This fungus was reproduced in rice, corn, and mixture of rice and bran media. The results showed that rice was the best medium for N. rileyi. The spore production in the media of rice, corn, and mixture of rice and bran media after three weeks cultivation age were 7,65 x 10"; 1, 78 x 1013; and 1,06 x 1013 spore-/ml, respectively.The pathogenicity tests of N. rileyi were employed against three instars (first, third, and fifth instar) of S. litura by spraying the soybean leaves with different concentration of spores. The spray volume was calculated based on the recommended field rate (500 I/ha). No mortality was observed on the first instar of S. litur. However, the third and fifth instar were found to be more susceptible to N. rileyi than the first instar with the LC50 values of 1,471 x 10° and 1,754 x 106 spore/ml respectively. Furthermore the LC95 of N. rileyi against the third and fifth instar was 1,319 x 10" and 2,574 x 1017 spore/respectively.