In order to study the interaction between h-BN epitaxial monolayer and Ni(111) substrate, near edge X-ray absorption fine structure (NEXAFS) spectroscopy is used. B K-edge NEXAFS spectra of h-BN/Ni(111) show a new π^* peak that does not appear in the spectrum of bulk h-BN. The modification of π^* band of h-BN is investigated by discrete variational X_α (DV-Xα) molecular orbital calculation with a model cluster. Taking into accounts core hole effect, the origin of the new π^* peak is explained in terms of partial density of states calculated by DV-Xα method. Theoretical approach clarifies that π^* orbital of h-BN is mainly hybridized with 4p orbital of Ni substrate. This leads to the conclusion that h-BN monolayer is chemisorbed on Ni(111) substrate.