To provide a safe and low cost flash irradiation device of a penetration printing plate with a simple structure, which consists of a small number of parts and obtains a safe and sure flash irradiation.

This flash irradiation device can process a stamp material 12 in response to a manuscript by developing a flash irradiation in a flash lamp 11 through a flash switch part 8 in interlocking with a lever 10 by contacting a power source 4 with the other end 2b of a thin plate piece conductor 2 only under the condition that the rotary position of the lever 10 gets more than the desired compressibility of the stamp material 12 under the state that the power source 4 for developing flashing is mounted on an elastic body 5.