During the course of a survey of sapstaining fungi in Korea, a Leptographium was isolated from Pinus densiflora and P. koraiensis logs, infested with the bark beetle Tomicus piniperda. The fungus grew optimally at 25 °C on 2% malt extract agar and showed a high level of tolerance to cycloheximide. The Leptographium has unusually short conidiophores and is morphologically similar to L. pini-densiflorae, L. lundbergii, L. yunnanense, and the Leptographium anamorph of Ophiostoma crassivaginatum. Comparisons of DNA sequence data for three gene regions, as well as morphological characteristics, confirmed that this fungus represents an undescribed taxon. We consequently provide the name Leptographium koreanum sp. nov. for it here.