A clamp device for transferring a construction material capable of eliminating manual handling of the construction material prior to transferring of the construction material, leading to labor saving. First and second brackets are connected to each other through a joint and a second bracket is engaged with a clamp. The first bracket is suitably mounted on an arm of a civil engineering machine such as a hydraulic shovel and the second bracket is provided with guide slits, in which shafts or pins of the clamp are engagedly fitted.