An endoscope includes an insertion portion including a distal end portion in which an image pickup unit is disposed, the insertion portion being configured to be inserted into an organ of a subject, an operation portion disposed at a proximal end of the insertion portion, and a sensor disposed in the operation portion, the sensor being configured to detect a pressure of a fluid in a flow passage passing through from the operation portion to a first opening of the distal end portion, the flow passage being configured to allow the fluid flowed into the operation portion to be flowed out from the first opening.