To provide a flash discharge lamp and a light irradiation device, for example, generating strong ultraviolet-ray with high efficiency, suitably improved for practical use for surface treatment.

The flash discharge lamp HFL comprises a transparent and thin airtight container SE; a pair of electrodes E, E sealed in both end parts of the airtight container SE; discharging media containing rare gas and mercury, sealed in the airtight container SE, and emitting light at discharge; and a trigger wire TW arranged near an outer periphery of the airtight container SE. The flash discharge lamp HFL performs a flash discharge triggered by an abrupt discharge of a capacitor in a direct current power source through the pair of electrodes E, E.