Anamorph and teleomorph of Diatrype stigma on the bed-log inoculated with oak-mushroom (Lentinula edodes) in Korea were observed and identified. As the characters of anamorph of Diatrype stigma, conidia were hyaline, falcate or slightly curve, and $1{sim}1.5{ imes}12.5{sim}17.5;{mu}m$, and conidia layer was confirmed under the bark. About teleomorph, perithecia $150{sim}200{ imes}450{sim}500;{mu}m$, with ostiole ($30{sim}40;{mu}m$, three- to four-sulcate). Size of ascus containing 8 ascospores was $5{sim}6{ imes}30{sim}40;{mu}m$. Ascospores were hyaline to pale brown, $1.5{sim}2{ imes}5{sim}7.5;{mu}m$ and mostly biguttulate.