PURPOSE: To form a flat glass structure by assembling plural panes of flat glass, composed of plural planar parts having a straight-line folded part and a specific nearly equal radius of curvature on the outer periphery of a curved surface at right angles to the curved part at a prescribed interval.

CONSTITUTION: A folding line is drawn with an electrically conductive coating such as a carbonaceous coating at a prescribed position in each pane of flat glass. Electrodes and sheathed heaters are installed at the ends thereof. A flexible heater is installed on the whole surface of the flat glass and a current is made to flow through the folding line to heat the flat glass at a prescribed temperature. The flat glass is then folded at 60-160 angle so as to provide the outer periphery with a radius of curvature within the range of 1-4 times the thickness of the glass and then annealed to prepare bent flat glass. The two panes 1 and 2 of the flat glass are then superposed through a spacer 3 made of Al, etc., so as to afford 3-60mm interval between the planar parts. A drying agent 4 is filled in the hollow part of the spacer 3 and a sealing material 6 such as butyl rubber is filled in the interval between the spacer and the flat glass. A caulking material 5 such as a silicone rubber is filled in the interval between the outside of the spacer 3 and the flat glass facing to the outside of the spacer 3 to provide the objective flat glass structure.