Maesopsis eminii (Engl.) is a commercial wood that is classified as fast-growing multifunctional species. The disease will inhibit plant growth as well as decrease the quality of timber. This research was aimed to identify types of pathogens, disease incidence, and severity of leaf blight disease in Maesopsis eminii seedlings. The methods were included field observations, isolation of symptomatic leaf blight, and subsequent test of Koch’s postulates. The isolates then observed both macroscopically and microscopically. The results of observations were indicated that the incidence of the disease was 99.44%, while the severity of the disease 8.85%. The isolation of symptomatic leaf blight was founded on eight kinds of isolate that have different colors. Then, the isolates were inoculated to Maesopsis eminii. Almost the entire of isolates can cause the symptoms of leaf blight. The result of Koch’s postulates was founded on two types of isolates that identically the same with the initial isolation. Finally, the pathogenicity test showed that isolates with 1.1 codes have the highest percentage value of disease incidence and severity than the other isolates. The identification results show that the isolate with 1.1 code is a type of fungus characterized by having sectional hyphae and contained conidia, which is included in the Deuteromycetes class.