A compact tube clamping device for inspecting an electric resistance welded tube quality. A lifting/lowering base including a tube support body is provided onto a fixed base. Clamp claws sandwich the tube support body. A claw drive body lifting/lowering independently of the lifting/lowering base is provided in the lifting/lowering base. Opposite side portions of the claw drive body are connected to opposite clamp claws by links to turn the opposite clamp claws in closing directions by lowering with respect to the lifting/lowering base. A first drive mechanism for the lifting/lowering base and a second drive body for lifting/lowering the claw drive body are provided to the fixed base. A lowering stroke of the claw drive body necessary for closing operations of the clamp claws is partially born by lifting of the lifting/lowering base in transferring the tube, thereby suppressing the lowering stroke of the claw drive body.