A support arrangement for supporting load in a transportation unit, includes a rod-like support member placed beside the load to support it and two parallel rails in the longitudinal direction of the transportation unit and at a distance from each other. The support member includes support ends for fastening to support points in the transportation unit so that the support member is perpendicular to the longitudinal axis of the transportation unit. Safe and easily implemented support for the load to be transported is achieved by arranging the support member to move along the inner walls of the rails and guided by the inner walls to set it against the load. The support arrangement includes an elongated flexible member and a tightening element for tightening the elongated flexible member against the load so that displacement of the load in relation to the rod-like member is prevented.