A light irradiation apparatus in which high peak irradiance is obtained and the heat influence on the article being irradiated with light is reduced, and also an inkjet printer which has such a light irradiation apparatus in which pictures with high image quality can be reliably made and the amount of heat influence on the recording medium is low is achieved using a light irradiation apparatus having a discharge lamp of the short arc type and a reflection component for reflecting the light of this discharge lamp. The light of the discharge lamp is radiated in a state in which it is focused by the reflection component so as to extending linearly on the light irradiation area. The inkjet printer has a head part with the above described light irradiation apparatus, the light from which sets ink of the photosetting type which has been applied to the recording medium