PURPOSE: To join the sheet-shaped bodies together preventing deviations by guiding them with a guide device when one body moves toward the other each being grasped with a support plate and a support bar.

CONSTITUTION: The guide device has a frame body 7A projected in the center of the support plate 7 with the wedge-shaped support bar 7B fitted loosely thereinto. The guide is placed across the upper portion 1A and the lower portion 1B whose walls are separately grasped with support plates 7 and support bars 7B. As the upper portion 1A is lowered with a bolt 6A being turned, it is guided by a clearance between the support plate 7 and the support bar 7B to assure that it joins the lower portion 1B accurately. Then, after the guide device is removed, a joint 1C is sealed with a welding rod 8 and a two-split angle 5, a through bolt 6 and a nut 6A are removed. If necessary, the joint is reinforced with a reinforcing layer 9 of glass-fiber polyester from outside.