A reading module of the present disclosure is provided with a light source, an optical system, and a sensor. The optical system images, as reading light, reflected light of light radiated from the light source to an illumination object. The sensor converts the reading light imaged by the optical system into an electric signal. The optical system is provided with a mirror array in which a plurality of reflection mirrors are disposed in an array in a prescribed direction and a plurality of aperture stop portions that adjust an amount of the reading light. Each of the reflection mirrors is disposed at a prescribed distance from an adjacent one of the reflection mirrors in a prescribed direction.