Ciboria batschiana, a fructicolous Discomycete, is a pathogen of Quercus serrata acorns, which contain considerable amounts of tannins in the cotyledons. It was hypothesized that the severity of C. batschiana infection may differ according to individual acorn tannin content. To examine this hypothesis, we investigated the relationship between survival of acorns to C. batschiana and tannin content, estimated non-destructively using near infrared spectroscopy analysis. In addition, an inoculation experiment showed that acorns with higher tannin contents were more resistant to C. batschiana than those with lower tannin contents. We conclude that infection success of C. batschiana differs with tannin content of individual acorns.