In a transmission case mounted on a FF type vehicle, the transmission case includes a resin side cover formed at a front side of the vehicle. The resin side cover constitutes a vehicle front side surface section of an oil storage section configured to store oil in the transmission case, and includes a protrusion disposed above an oil surface of the oil stored in the oil storage section and protruding toward the front side of the vehicle to constitute the foremost section of the transmission case and a fragile section disposed between the protrusion and the oil surface of the oil and extending transversely in a lateral direction.