An image reading apparatus provided with an illuminating apparatus including a plurality of parallel rows of light source groups (220a, 220b) each having a plurality of light-emitting elements (212a, 212b) for irradiating light to an original, wherein the light-emitting elements (212a, 212b) are arranged in a main scanning direction, and an original reading portion that reads light reflected from the original illuminated by the illuminating apparatus, the image reading apparatus comprising: a setting portion configured to set a light amount of each light-emitting element (212a, 212b) in the plurality of rows of light source groups (220a, 220b), wherein the light-emitting elements (212a, 212b) in the plurality of rows of light source groups (220a, 220b) illuminate an irradiated face (Gd) of the original at a constant pitch within the same light source group (220a, 220b) and at different pitches from each other among the plurality of rows of light source groups (220a, 220b), and if an illumination distribution that indicates uneven illuminance due to repeated areas of brightness and darkness on the irradiated face (Gd) of the original in the main scanning direction falls out of a predetermined reference range of uneven illuminance, the light-emitting elements (212a, 212b) in the plurality of rows of light source groups (220a, 220b) are set by the setting portion to have a light amount with which the illumination distribution falls within the reference range, wherein at least one light source group (220a, 220b) among the plurality of rows of light source groups (220a, 220b) includes a plurality of wires each connecting the plurality of light-emitting elements (212a, 212b) in series in units of a plurality of light-emitting elements (212a, 212b), wherein between the plurality of light-emitting elements (212a, 212b) on a single wire among the plurality of wires, the plurality of light-emitting elements (212a, 212b) on another wire are separately arranged in a row in the same arrangement order in the main scanning direction, wherein each of the plurality of wires in the at least one light source group (220a, 220b) connects in series the light-emitting elements (212a, 212b) arranged in the main scanning direction in the at least one light source group (220a, 220b) in units of the number of light-emitting elements (212a, 212b) obtained by dividing a length of a least common multiple of the pitches in the plurality of rows of light source groups (220a, 220b) by a length of the pitch between the light-emitting elements (212a, 212b) in the at least one light source group (220a, 220b). a setting portion configured to set a light amount of each light-emitting element (212a, 212b) in the plurality of rows of light source groups (220a, 220b), wherein the light-emitting elements (212a, 212b) in the plurality of rows of light source groups (220a, 220b) illuminate an irradiated face (Gd) of the original at a constant pitch within the same light source group (220a, 220b) and at different pitches from each other among the plurality of rows of light source groups (220a, 220b), and if an illumination distribution that indicates uneven illuminance due to repeated areas of brightness and darkness on the irradiated face (Gd) of the original in the main scanning direction falls out of a predetermined reference range of uneven illuminance, the light-emitting elements (212a, 212b) in the plurality of rows of light source groups (220a, 220b) are set by the setting portion to have a light amount with which the illumination distribution falls within the reference range, wherein at least one light source group (220a, 220b) among the plurality of rows of light source groups (220a, 220b) includes a plurality of wires each connecting the plurality of light-emitting elements (212a, 212b) in series in units of a plurality of light-emitting elements (212a, 212b), wherein between the plurality of light-emitting elements (212a, 212b) on a single wire among the plurality of wires, the plurality of light-emitting elements (212a, 212b) on another wire are separately arranged in a row in the same arrangement order in the main scanning direction, wherein each of the plurality of wires in the at least one light source group (220a, 220b) connects in series the light-emitting elements (212a, 212b) arranged in the main scanning direction in the at least one light source group (220a, 220b) in units of the number of light-emitting elements (212a, 212b) obtained by dividing a length of a least common multiple of the pitches in the plurality of rows of light source groups (220a, 220b) by a length of the pitch between the light-emitting elements (212a, 212b) in the at least one light source group (220a, 220b).