An illumination apparatus includes: a light source; a rod-like light guide having an incident surface that enters light from the light source that is disposed on one side in a main-scan direction, a diffusing surface that diffuses light that enters from the incident surface, and an emission surface that linearly emits light towards a bill; and a reflection member having a reflection surface that reflects light diffused by the diffusing surface to the light guide. The light guide has a locking projection that is locked in the reflection member on one side in the main-scan direction. The reflection member has a locking hole in which the locking projection is locked. A cut-out portion at which one part is cut out is formed in the locking hole.