A light scanning apparatus comprising: a light source; a deflector configured to deflect a light flux from the light source; and an imaging optical system configured to guide the light flux deflected at the deflector onto a scanned surface, wherein the imaging optical system consists of a single imaging optical element, wherein, on an optical axis of the imaging optical system, the following conditions are satisfied 0.15 ≤ T 2 / Sk ≤ 0.3 0.03 ≤ d / K ≤ 0.08 where T2 represents the distance from a deflecting surface of the deflector to an exit surface of the imaging optical element, Sk represents the distance from the exit surface of the imaging optical element to the scanned surface, d represents the thickness of the imaging optical element, and K represents an imaging coefficient at an on-axis image height Y 0 =0 corresponding to an on-axis scanning angle θ 0 =0°, wherein K is constant from the on-axis image height Y 0 to a maximum off-axis image height Y max corresponding to a maximum off-axis scanning angle θ max, wherein when denoting image heights from the on-axis image height Y 0 to the maximum off-axis image height Y max as Y(θ), scanning angles from the on-axis image height Y 0 to the maximum off-axis image height Y max as θ, and a scanning properties coefficient as B, the scanning property of the imaging optical system is determined by Y θ = K / B × tan B × θ, wherein B is constant from the on-axis image height Y 0 =0 to the maximum off-axis image height Y max and satisfies the condition 0.3 ≤ B ≤ 0.6, wherein the light scanning apparatus further comprises a control unit configured to control a light-emitting timing of the light source in accordance with partial magnification shift of the imaging optical element, expressed by tan 2 (B×θ). a light source; a deflector configured to deflect a light flux from the light source; and an imaging optical system configured to guide the light flux deflected at the deflector onto a scanned surface, wherein the imaging optical system consists of a single imaging optical element, wherein, on an optical axis of the imaging optical system, the following conditions are satisfied 0.15 ≤ T 2 / Sk ≤ 0.3 0.03 ≤ d / K ≤ 0.08 where T2 represents the distance from a deflecting surface of the deflector to an exit surface of the imaging optical element, Sk represents the distance from the exit surface of the imaging optical element to the scanned surface, d represents the thickness of the imaging optical element, and K represents an imaging coefficient at an on-axis image height Y 0 =0 corresponding to an on-axis scanning angle θ 0 =0°, wherein K is constant from the on-axis image height Y 0 to a maximum off-axis image height Y max corresponding to a maximum off-axis scanning angle θ max, wherein when denoting image heights from the on-axis image height Y 0 to the maximum off-axis image height Y max as Y(θ), scanning angles from the on-axis image height Y 0 to the maximum off-axis image height Y max as θ, and a scanning properties coefficient as B, the scanning property of the imaging optical system is determined by Y θ = K / B × tan B × θ, wherein B is constant from the on-axis image height Y 0 =0 to the maximum off-axis image height Y max and satisfies the condition 0.3 ≤ B ≤ 0.6, wherein the light scanning apparatus further comprises a control unit configured to control a light-emitting timing of the light source in accordance with partial magnification shift of the imaging optical element, expressed by tan 2 (B×θ).