A vehicle bottom structure for supporting a battery pack comprising: a pair of side members that are disposed on both sides of a vehicle in a width direction and extend in a front-rear direction of the vehicle; and a plurality of cross members that extend in the width direction of the vehicle, are joined to the side members at both end parts, and configured to support a bottom of the battery pack disposed under a floor panel between the side members , from below; and a front-rear direction reinforcing member that is joined on the cross members so as to extend in the front-rear direction of the vehicle and cross the cross members , characterized in that : the cross member and the front-rear direction reinforcing member are each a long member having a hat-shaped cross-section and including: a groove-shaped part including a bottom plate and upright plates formed on both ends of the bottom plate in the width direction; and a flange connected to an open end of the groove-shaped part , and the front-rear direction reinforcing member has cutouts that are formed at positions of the upright plates to intersect with the cross member and formed in U-shapes along a convex shape of the groove-shaped part of the cross member , and the bottom plate of the groove-shaped part of the front-rear direction reinforcing member is disposed on and joined to the bottom plate of the groove-shaped part of the cross member . a pair of side members that are disposed on both sides of a vehicle in a width direction and extend in a front-rear direction of the vehicle; and a plurality of cross members that extend in the width direction of the vehicle, are joined to the side members at both end parts, and configured to support a bottom of the battery pack disposed under a floor panel between the side members , from below; and a front-rear direction reinforcing member that is joined on the cross members so as to extend in the front-rear direction of the vehicle and cross the cross members , characterized in that : the cross member and the front-rear direction reinforcing member are each a long member having a hat-shaped cross-section and including: a groove-shaped part including a bottom plate and upright plates formed on both ends of the bottom plate in the width direction; and a flange connected to an open end of the groove-shaped part , and the front-rear direction reinforcing member has cutouts that are formed at positions of the upright plates to intersect with the cross member and formed in U-shapes along a convex shape of the groove-shaped part of the cross member , and the bottom plate of the groove-shaped part of the front-rear direction reinforcing member is disposed on and joined to the bottom plate of the groove-shaped part of the cross member . the cross member and the front-rear direction reinforcing member are each a long member having a hat-shaped cross-section and including: a groove-shaped part including a bottom plate and upright plates formed on both ends of the bottom plate in the width direction; and a flange connected to an open end of the groove-shaped part , and the front-rear direction reinforcing member has cutouts that are formed at positions of the upright plates to intersect with the cross member and formed in U-shapes along a convex shape of the groove-shaped part of the cross member , and the bottom plate of the groove-shaped part of the front-rear direction reinforcing member is disposed on and joined to the bottom plate of the groove-shaped part of the cross member . <EOS>