Conduit switching piston, and endoscope

A conduit switching piston that is fitted and inserted in an advanceable and retractable manner into a cylinder to which a plurality of conduits are connected, the conduit switching piston being configured to switch communication states of the plurality of conduits, comprising:

• a shaft member having a cross-section in a radial direction that is formed in a circular shape;
• a plurality of seal portions formed having a set interval with respect to each other along an extending direction of the shaft member on an outer circumferential face of the shaft member, and having an outer circumference that elastically contacts an inner circumferential face of the cylinder;
• a pair of flat portions formed by cutting out a part of the outer circumferential face along the extending direction on each of two sides of the outer circumferential face with a central axis of the shaft member being interposed between the two sides, and having two edge portions facing each other on the outer circumferential face and extending along the extending direction;
• and
• a connecting portion configured to connect two seal portions among the plurality of seal portions which are adjacent along the extending direction, and formed on the pair of flat portions integrally with the seal portions.