Vehicle battery mounting structure

A vehicle battery mounting structure comprising:

• a battery frame that is disposed at a vehicle lower side of a floor panel, supports a battery, and is made from resin;
• a ductile member that comprises a main body joined to the battery frame and a flange contiguously formed at a vehicle width direction outside end portion of the main body, the flange having a hole, and the ductile member being fastened and fixed to a lower face of the floor panel by a fastener inserted through the hole of the flange;
• and
• a fastening portion that is formed in a region including the hole of the flange, the region having a substantially hat shaped cross-section profile projecting toward a vehicle upper side from recessed portions and the region having ridge lines adjacent to the hole and between the fastening portion and the recessed portions at both vehicle front-rear direction sides of the hole, the ridge lines extending along a vehicle width direction and having a curved or bent shape at vehicle width direction inner sides thereof, the ridge lines bending toward directions heading away from the hole adjacent to the ridge lines in plan view.