In a comprehensive research project on bat viruses, we successfully isolated a novel herpesvirus from the spleen of a greater horseshoe bat (Rhinolophus ferrumequinum) in Japan using a cell line established from the kidney of the same bat. This herpesvirus was a novel gammaherpesvirus (Rhinolophus gammaherpesvirus 1; RGHV-1), which belonged to the genus Percavirus. The whole RGHV-1 genome (147,790 bp) showed that 12 of the 84 genes predicted to contain open reading frames did not show any homology to those of other herpesviruses.