Mycoviruses from Metarhizium anisopliae have been extensively studied, but their sequences have yet to be deposited in the NCBI database. In the present study, we characterized a new partitivirus obtained from the entomogenous fungus Metarhizium brunneum, named "Metarhizium brunneum partitivirus 1" (MbPV1). The complete genome of MbPV1, determined by metagenomic sequencing, RT-PCR, and RACE, comprised two dsRNA segments of 1,829 bp and 1,720 bp, respectively. Both dsRNAs contained a single open reading frame (ORF), encoding a putative RNA-dependent RNA polymerase (RdRp) and a coat protein (CP), respectively. The sequences of the RdRp and CP showed the highest similarity (61.4% and 44.4% identity, respectively) to those of Colletotrichum eremochloae partitivirus 1 (CePV1), which were obtained from the NCBI database. A phylogenetic tree based on the RdRp sequence showed that MbPV1 clustered with members of the proposed genus "Epsilonpartitivirus", belonging to family Partitiviridae. Here, we propose that MbPV1 is a member of a new species of the proposed genus "Epsilonpartitivirus". This is the first sequence data report of a new mycovirus from a member of the genus Metarhizium.