A sizing device is installed on a downstream side in an extrusion direction of a die. A table having two sizing unit attachment portions which are adjacent to each other in a lateral direction orthogonal to the extrusion direction. The table is provided at a device body so as to be laterally movable between a first position where one of the two sizing unit attachment portions is at a production position and the other of the two sizing unit attachment portions is at a standby position, and a second position where the other of the two sizing unit attachment portions is at the production position and the one of the two sizing unit attachment portions is at the standby position. A sizing unit for production configured to perform cooling and sizing in practice is detachably attached to one of the two sizing unit attachment portions at the production position to coincide with an extrusion line. A sizing unit for replacement is detachably attachable to the other of the two sizing unit attachment portions at the standby position.