A paper sheet processing apparatus including a housing part capable of stacking a paper sheet in a stable condition. A bill processing apparatus includes: a bill housing part capable of stacking the bill having been inserted into a bill insertion slot. The bill housing part includes a regulatory member having an opening through which a bill to be received; and a contact face which regulates a movement of the bill by contacting. The regulatory member is configured to make a coefficient of friction on the contact face contacting the bill greater than a coefficient of friction caused between stacked and housed bills.