In a focal plane shutter of the kind having a plurality of divided blades pivotally arranged to be turnable on driving arms in an overlapped state, the weight of the blades is reduced by making them from very thin material; the blades are reinforced with embossed protrusions which are formed in the longitudinal direction of the blades for the purpose of preventing them from flexing and being damaged during their travel. Each of the embossed protrusions is within the difference in stepped height between the surfaces of the blades and the heads of blade carrying studs disposed on the driving arms. Therefore, the shutter can be smoothly operated without increasing the thickness of the blades as a whole.