Boletus kermesinus, a new species of Boletus section Luridi, is fully described and illustrated based on the materials collected in subalpine coniferous forests of central Honshu, Japan. It has distinctive features of darkred basidiomata having distinct viscidity in the pileus surface, usually unchanging flesh, discolorous red pores, and an entirely reticulate stipe becoming coarsely laceraterimose with age.