A combination crane A is formed by connecting two crawler cranes 1L and 1R. Each crawler crane is provided with at least a lower propelling body 3 which can be propelled by crawlers 2, an upper revolving body 5 rotatably mounted on the lower propelling body 3 by a swing unit 4 provided between them, a boom 6 whose base section is tiltably supported on the upper revolving body, a tilting mechanism 10 that raises and lowers the boom and a hoist mechanism that hoists and lowers the lifting members 12 hung by a hoist rope 11 from the top of the boom. Both upper swing bodies of two cranes are connected together with a connecting beam 20. Swing motion is performed by driving the one crawler crane to move around the other crawler crane which is free to rotate and is locked against propulsion.