A lower vehicle-body structure of a vehicle may include: a floor panel; a side sill; and a frame member that extends in the front-rear direction on the vehicle-width-direction inner side of the side sill and includes a front-rear extended portion that is in abutment against the side sill on the vehicle-width-direction inner side and extends in the vehicle front-rear direction along the side sill. The front-rear extended portion may include: a bottom face portion; an inner wall portion; and an inner-side flange that extends to the vehicle-width-direction inner side from a distal end portion of the inner wall portion and is joined to the floor panel. Deformation facilitating facilitators that facilitate deformation of the bottom face portion in the vehicle width direction when a collision load in the vehicle width direction is input may be formed in the bottom face portion.