Provided is a pressure detection device comprising a pressure detection unit configured to detect pressure transmitted to a pressure detecting surface; a flow passage unit including a flow passage configured to allow fluid to flow along a flow direction from an inflow port to an outflow port, and a pressure transmitting surface configured to transmit pressure of fluid flowing through the flow passage to the pressure detecting surface; and a mounting mechanism by which the flow passage unit is removably mounted on the pressure detection unit. The pressure detecting surface includes a sliding layer having a sliding property for when the pressure detecting surface comes in contact with the pressure transmitting surface.