A printer includes an upper unit which opens and closes about a fulcrum lying at a rear position of a lower unit, and a paper path which is opened by opening the upper unit. A sensor unit is attached to the lower unit and includes a lower sensor holder and an upper sensor holder which are disposed in opposition to each other via the paper path. The paper path can be opened by pivoting the upper sensor holder relative to the lower sensor holder. When the upper unit is closed, the upper sensor holder is also closed in accordance with a closing pivoting motion of the upper unit.