Virus populations of uncultivated fungi remain scarcely studied. In the present study, we characterized a new partitivirus isolated from the false morel mushroom Gyromitra esculenta, named "Gyromitra esculenta partitivirus 1" (GePV1). The complete genome of GePV1, whose sequence was determined by combining high-throughput sequencing and RLM-RACE approaches, comprises two dsRNA segments of 1971 bp and 1799 bp, respectively. Each dsRNA genome segment contains a single open reading frame (ORF), encoding a putative RNA-dependent RNA polymerase (RdRp) and a capsid protein (CP), respectively. The sequences of the RdRp and CP exhibited the highest similarity (69.77% and 47.00% identity, respectively) to those of Rosellinia necatrix partitivirus 2 (RnPV2). Phylogenetic analysis based on the CP and RdRp sequences demonstrated that GePV1 clusters within a clade that includes members of the genus Alphapartitivirus, family Partitiviridae. We propose that GePV1 is a new member of the genus Alphapartitivirus. This is the first study reporting on a new partitivirus identified in the false morel mushroom Gyromitra esculenta.