To provide a printer enabling fine printing suitable for a paper sheet without troubling a user by automatically discriminating a paper sheet type and performing printing setting based on a result thereof.

This mechanism is provided with a pressure sensor capable of butting to and retreating from the paper sheet in a paper carrying passage. The paper sheet type is discriminated from a pressure value detected by the pressure sensor butting to the paper sheet. A distance measuring means is provided for measuring a separated distance between a member butting to the paper sheet in a certain amount and the paper sheet separated by the member. The paper sheet type is discriminated from the separated distance measured by the distance measuring means.