PURPOSE: To facilitate, simplify and quicken the transport of the long size material by a method wherein the long size material is bridgedly mounted over cross blocks bridged between struts installed in upright position at the right and left sides of a mounting platform and clamped with clamping ropes spanned between said struts.

CONSTITUTION: Cross blocks 4 are bridged between the struts 2 and 3 installed in upright position at the right and left sides of the mounting platform 1 and as well as wooden upper cross blocks 5 are laid on the cross blocks 4. The whole loading device is reinforced and stabilized with reinforcement columns 6, 7 and 8 and foot columns 9 and 10. A pair of long size material positioning sliders 13 and 14 are slidably and positioning-capably provided over the blocks 4 and 5. The clamping ropes spanning between the struts 2 and 3 are pulled downward by a moving-block type clamping means 29. The clamping means 29 consists of a winch 30, a drag rope 31, a fixed block 29, a moving block 33 and the fixed end 34 of the rope 31. The long size material D is mounted on the cross blocks 5 and positioned with the sliders 13 and 14 and, after that, clamped with the clamping ropes 28.