The invention relates to a support arrangement for supporting load in a transportation unit (2'), the support arrangement comprising a rod-like support member (4') to be placed beside the load (1') to support it and two parallel rails (13') in the longitudinal direction of the transportation unit and at a distance from each other, and the support member (4') comprises support ends (14') to be fastened to support points in the transportation unit so that the support member (4') is at right angles to the longitudinal axis of the transportation unit and locked in place in such a way that free movement of the support member relative to the transportation unit is prevented. To achieve good and easily implemented support for the load (1') to be transported, the support member (4') is arranged to move along the inner walls of the rails (13') and guided by the inner walls to set it against the load; the support ends (14') of the support member (4') have gripping edges that are arranged to bite into the inner walls of the rails (13'), when the support member is in its locked position; and the support arrangement comprises an elongated flexible member (9') and a tightening means (12') for turning the support member (4') and its support end (14') so that the gripping edges of the rod-like support member wedge by biting into the inner walls of the rails (13') in order to keep the support member in its locked position.