Light irradiation device, the light irradiation module and the printing apparatus

Also a plurality of light emitting elements though a device mounted on a single substrate, to provide an optical illumination device that can increase the light intensity per unit area. A light irradiation device 1 for irradiating light to an object to move relative the substrate 10, which are arranged on a main 11a of the substrate 10, a plurality which is located on the upstream side in the moving direction of the object a first light emitting element group 20Aa, a plurality of second light emitting element group 20Ab located downstream, a plurality of first lens 17a covering the plurality of first light emitting element group 20Aa and the second light emitting element group 20Ab and and a second lens 17b, the optical axis of the light emitted through each of the plurality of first lens 17a is toward the downstream side in the moving direction with respect to the normal to the one main surface 11a of the substrate 10 are inclined, the optical axis of the light emitted through each of the plurality of second lens 17b is inclined toward the upstream side.