To provide a mixed medium processing unit of high reliability capable of taking in media of various thicknesses with high flexibility and capable of taking in even a deformed medium with its end doubled, in the case of a mixed medium processing unit 102 for taking in and processing media of different kinds such as payment forms and passbooks.

This mixed medium processing unit has a medium interference part 31 functioning as a foreign matter insertion preventing shutter during standby to receive a medium and guiding the front end of an inserted medium P to between a pair of rollers 21 and 22 of a take-in part 20 when the medium P is inserted into a reception port 1, and is further provided with an insertion guide plate 23 evacuatable by the interference of the medium P caught between the rollers with the interference part 31.