A floor panel for a floor covering includes a pair of two opposite sides having coupling parts allowing to couple the floor panel to similar floor panels. The coupling parts, in a coupled condition, provide locking in vertical and horizontal directions. The floor panel has a core including two core material parts provided as a sandwich structure between an upper layer and a bottom layer, and respectively extending up to one of the two sides. A locking element is in the form of an insert located at one of the sides of the coupling parts, and is mounted in the core material part. The locking element is of the type which, in the coupled condition of two of such floor panels, effects a locking in a vertical direction. The two core material parts include a different basic material or a basic material with different properties.