A frame structure for a vehicle includes: an inner panel connected to a side member and defining an inner side of a rear part of the side member; an outer panel connected to a rear side of the side member and coupled to an outer side of the inner panel defining a closed cross-section together with the inner panel and defining an outer side of the rear part of the side member; an opening portion formed below the inner and outer panels partially opening the closed cross-section so that a front end of a rear suspension arm can be inserted into the opening portion; and a reinforcing member disposed in the opening portion defining the closed cross-section together with the outer panel and the inner panel and configured to close an internal space in the outer and inner panels.