DEFECT DETECTOR

PURPOSE:To perform accurate defect detection by arranging projecting and photodetecting heads in a parting gap on the sides of fixed guide rails provided slantingly to its conveyance direction. CONSTITUTION:Conveying devices 6a and 6b convey a flat body W to be measured along its conveyance path in the order of a carry-in position 2, the 1st and the 2nd detection positions 3a and 3b, and a carry-out position. Then, the fixed guide rails 10a and 10b for guiding the parted body W to be measured are provided along the conveyance path slantingly to the conveyance direction, and movable guide rails 11a and 11b which guide the body W to be measured while pressing it elastically against the guide rails 10a and 10b are provided while enabled to move to and away from the fixed guide rail 10a and 10b; and projecting and photodetecting heads 15a and 15b are arranged in the parting gap 12 on the sides of the fixed guide rails 10a and 10b provided slantingly to the conveyance direction.