A light scanning unit , comprising: a light source , an optical system including a first optical unit and a second optical unit , and an optical deflector , wherein: the light source includes at least two light-emitting points for diverging light beams; the at least two light-emitting points are distributed along a straight distribution line; and an angle between an extension direction of the distribution line of the at least two light-emitting points and the main scanning direction or the secondary scanning direction of the light scanning unit includes an acute angle (O), wherein the main scanning direction is perpendicular to the secondary scanning direction; the first optical unit is configured to collimate at least two light beams emitted from the light source along the main scanning direction and to focus the at least two light beams emitted from the light source along the secondary scanning direction; the optical deflector is configured to deflect and scan at least two light beams emitted from the first optical unit as the optical deflector rotates; and the second optical unit is configured to make the at least two light beams deflected and scanned by the optical deflector form an image on a scanned surface ; characterized in that a following expression is satisfied: (βs/βm) 2 >0.6, wherein: βm denotes a magnification of the optical system along the main scanning direction; and βs denotes a magnification of the optical system along the secondary scanning direction; and the magnification βm of the optical system along the main scanning direction and the magnification βs of the optical system along the secondary scanning direction also satisfy a following expression: β s / β m > 0.77 . the light source includes at least two light-emitting points for diverging light beams; the at least two light-emitting points are distributed along a straight distribution line; and an angle between an extension direction of the distribution line of the at least two light-emitting points and the main scanning direction or the secondary scanning direction of the light scanning unit includes an acute angle (O), wherein the main scanning direction is perpendicular to the secondary scanning direction; the first optical unit is configured to collimate at least two light beams emitted from the light source along the main scanning direction and to focus the at least two light beams emitted from the light source along the secondary scanning direction; the optical deflector is configured to deflect and scan at least two light beams emitted from the first optical unit as the optical deflector rotates; and the second optical unit is configured to make the at least two light beams deflected and scanned by the optical deflector form an image on a scanned surface ; characterized in that a following expression is satisfied: (βs/βm) 2 >0.6, wherein: βm denotes a magnification of the optical system along the main scanning direction; and βs denotes a magnification of the optical system along the secondary scanning direction; and the magnification βm of the optical system along the main scanning direction and the magnification βs of the optical system along the secondary scanning direction also satisfy a following expression: β s / β m > 0.77 . βm denotes a magnification of the optical system along the main scanning direction; and βs denotes a magnification of the optical system along the secondary scanning direction; and the magnification βm of the optical system along the main scanning direction and the magnification βs of the optical system along the secondary scanning direction also satisfy a following expression: β s / β m > 0.77 . <EOS>