A stationary frame (20) is in the form of a box body (28) by which mutually telescopic lateral extension frames (21, 22) are slidably supported, thereby providing a spreader (16) which is light in weight and has no bent or torsion of the extension frames. Support of the extension frames (21, 22) by the support rollers (37) mounted on the opposite ends of the stationary frame (20) reduces the drive force upon extension or contraction of the extension frames (21, 22), and provision of the rail (43) and cushioning member (44) between the extension frames (21, 22) and the stationary frame (20) reduces the impact load applied on the extension frames (21, 22) when the spreader (16) is hoisted down onto the container (4).