To provide a rod light guide having improved uniformity of light intensity in the main scanning direction.
The rod light guide 20 has an outside face consisting of right and left end faces 21, 22, a side face 23 as an emission plane, a side face 24 opposed to the side face 23 as the emission plane, side faces 25, 26 adjacent to the side face 23 as the emission plane, and chamfered portions 27, 28 formed between the side face 24 and each of the side faces 25, 26. On the side face 24, a main pattern 30 for light scattering is formed with while paint. The main pattern 30 has applied portions 30a and non-applied portions 30b alternately in the longitudinal direction. The width of the applied portion 30a is smaller at the side closer to a light emitting source 11 and gradually greater toward the opposite-side end face. On the side face 25, a sub-pattern 31 for light scattering is formed with while paint.