The invention relates to a bumper beam (B) comprising a main cross member (1) and a cross member part (2) fixedly attached to said main cross member (1). Said cross member part (2) forms in itself or together with one or more portions of the main cross member (1) a closed chamber (C) in a cross section of the bumper beam and is arranged at an upper side (11) or at a lower side (12) of said main cross member (1). Said closed chamber (C) abuts and extends over only a portion of said upper side (11) or said lower side (12) of said main cross member (1) as seen in the cross direction of said main cross member (1) and over essentially the entire length and in a longitudinal direction of said main cross member (1). Said main cross member (1) together with said cross member part (2) form a closed main chamber (M).