a 1 40 b 1 and so on second heat insulating plates 40 a 2 40 b 2 and so on and second heat insulating plates 40 a 3 40 b 3 and so on and the second heat insulating plates 40 a 2 40 b 2 and so on and the second heat insulating plates 40 a 3 40 b 3 and so on are disposed facing the surfaces of both width direction end portions of the glass sheet g however as shown in fig6 since the second heat insulating plates 40 a 2 40 b 2 and so on and the second heat insulating plates 40 a 3 40 b 3 and so on are disposed so that the width thereof exceeds that of the glass sheet g the portions not occupied by the downflow of the glass sheet g form spaces sandwiched by the end faces of the pairs of second heat insulating plates 40 a 2 40 b 2 and so on or second heat insulating plates 40 a 3 40 b 3 and so on the second heat insulating plates 40 a 2 40 b 2 and so on and the second heat insulating plates 40 a 3 40 b 3 and so on may therefore further comprise two small heat insulating plates in order to reduce the amount of the space described above in the present modification heat insulating members 140 a the same configuration applying to the other heat insulating members hereinafter are each composed of one first heat insulating plate.