A multi-laser scanning unit (LSU) in which scanning lines incident parallel onto a photoreceptor have the same scanning direction. The multi-laser scanning unit includes: a driving source for providing a rotatory force; a deflection disk installed around a rotary shaft of the driving source having at least two sectors with a hologram pattern for diffracting and deflecting incident light, for scanning light through rotation; at least two light sources installed facing one surface of the deflection disk for irradiating light lines onto predetermined points in the at least two sectors of the deflection disk, the predetermined points are symmetrical by the rotary center of the deflection disk; a light path changing portion for changing traveling paths of the plurality of scanning lines formed by the rotation of the deflection disk, such that the centers of the scanning lines or extended imaginary lines of the scanning lines pass the rotary axis of the deflection disk; and a scanning direction changing portion for changing the scanning direction of one scanning line scanned by the deflection disk in the opposite scanning direction, such that all the scanning lines scan an image in the same scanning direction.