A light irradiation device for applying light to a target object under relative movement, comprising: a base; a plurality of light-emitting element groups (20A, 20Aa, 20Ab, 20Ac), each of groups having a plurality of light-emitting elements, the plurality of light-emitting elements being arranged in a matrix form on an upper surface of the base; and a plurality of lenses (17, 17a, 17b, 17c) configured to cover the light-emitting element groups (20A, 20Aa, 20Ab, 20Ac), respectively, the plurality of lenses (17, 17a, 17b, 17c) radiating light emitted from the light-emitting element groups (20A, 20Aa, 20Ab, 20Ac) outwardly, wherein the plurality of light-emitting element groups (20A, 20Aa, 20Ab, 20Ac) comprise a plurality of first light-emitting element groups located on an upstream side in a movement direction in which the target object is moved relative to the light irradiation device, and a plurality of second light-emitting element groups located on a downstream side in the movement direction, the plurality of lenses (17, 17a, 17b, 17c) comprise a plurality of first lenses which cover the plurality of first light-emitting element groups, respectively, and a plurality of second lenses which cover the plurality of second light-emitting element groups, respectively, the plurality of first lenses and the plurality of second lenses are plano-convex lenses, a center of a bottom surface of each of the plurality of first lenses as seen in a plan view is located at the downstream side in the movement direction with respect to a centroid of the plurality of light-emitting elements provided in the first light-emitting element group corresponding to the each of the plurality of first lenses as seen in a plan view, such that an optical axis of light emitted through each of the plurality of first lenses is inclined toward the downstream side in the movement direction with respect to a normal to the upper surface of the base, and a center of a bottom surface of each of the plurality of second lenses as seen in a plan view is located at the upstream side in the movement direction with respect to a centroid of the plurality of light-emitting elements provided in the second light-emitting element group corresponding to the each of the plurality of second lenses as seen in a plan view, such that an optical axis of light emitted through each of the plurality of second lenses is inclined toward the upstream side in the movement direction with respect to the normal to the upper surface of the base. a base; a plurality of light-emitting element groups (20A, 20Aa, 20Ab, 20Ac), each of groups having a plurality of light-emitting elements, the plurality of light-emitting elements being arranged in a matrix form on an upper surface of the base; and a plurality of lenses (17, 17a, 17b, 17c) configured to cover the light-emitting element groups (20A, 20Aa, 20Ab, 20Ac), respectively, the plurality of lenses (17, 17a, 17b, 17c) radiating light emitted from the light-emitting element groups (20A, 20Aa, 20Ab, 20Ac) outwardly, wherein the plurality of light-emitting element groups (20A, 20Aa, 20Ab, 20Ac) comprise a plurality of first light-emitting element groups located on an upstream side in a movement direction in which the target object is moved relative to the light irradiation device, and a plurality of second light-emitting element groups located on a downstream side in the movement direction, a plurality of first light-emitting element groups located on an upstream side in a movement direction in which the target object is moved relative to the light irradiation device, and a plurality of second light-emitting element groups located on a downstream side in the movement direction, the plurality of lenses (17, 17a, 17b, 17c) comprise a plurality of first lenses which cover the plurality of first light-emitting element groups, respectively, and a plurality of second lenses which cover the plurality of second light-emitting element groups, respectively, a plurality of first lenses which cover the plurality of first light-emitting element groups, respectively, and a plurality of second lenses which cover the plurality of second light-emitting element groups, respectively, the plurality of first lenses and the plurality of second lenses are plano-convex lenses, a center of a bottom surface of each of the plurality of first lenses as seen in a plan view is located at the downstream side in the movement direction with respect to a centroid of the plurality of light-emitting elements provided in the first light-emitting element group corresponding to the each of the plurality of first lenses as seen in a plan view, such that an optical axis of light emitted through each of the plurality of first lenses is inclined toward the downstream side in the movement direction with respect to a normal to the upper surface of the base, and a center of a bottom surface of each of the plurality of second lenses as seen in a plan view is located at the upstream side in the movement direction with respect to a centroid of the plurality of light-emitting elements provided in the second light-emitting element group corresponding to the each of the plurality of second lenses as seen in a plan view, such that an optical axis of light emitted through each of the plurality of second lenses is inclined toward the upstream side in the movement direction with respect to the normal to the upper surface of the base.