A recording medium processing apparatus includes a housing that accommodates a processing unit, which is capable of processing a recording medium, and that has an internal space a part of which is open; an internal stacker that is disposed in the internal space and that allows the recording medium to be stacked thereon; a light source that is disposed in a part of the internal stacker and that emits a light beam toward a predetermined position on the internal stacker, the light beam notifying a user of a state in which the recording medium is or is not stacked on the internal stacker; and a reflection member that is disposed in a part of the internal stacker and that reflects the light beam from the light source laterally outward from the internal stacker.