Symptoms similar to anthracnose were observed on Amaranthus mangostanus in Sancheon-gun, Gyeongnam province, where the plants were autogenously formed community. The symptoms were appeared in stem and spread, eventually whole plants died. Mycelial colony of the isolate was whitish gray to dark gray on potato dextrose agar. Conidia were single celled, colorless, cylindrical and measured as $10.5{sim}21.7{ imes}3.8{sim}6.0{mu}m$. Appressoria were dark brown, ovate to obovate and sized as $5.6{sim}13.7{ imes}4.6{sim}11.4{mu}m$. Perithecia were brown to black in color and shaped as globose to obpyriform and sized as $79.7{sim}286.7{mu}m$. Asci had eight ascospores and sized as $47.7{sim}89.7{ imes}8.1{sim}13.3{mu}m$. Ascospores were slightly curved at the center cylindrical, fusiform and measured $9.3{sim}20.3{ imes}4.6{sim}6.3{mu}m$. Optimum temperature for growth was $30^{circ}C$. On the basis of morphological characteristics and pathogenicity test to host plants, the fungus was identified as Glomerella cingulata. This is the first report on the Anthracnose of Amaranthus mangostanus caused by Glomerella cingulata in Korea.