A probe including a catheter sheath, a shaft inserted inside the catheter sheath, and an attachment portion detachably attached to a rotational drive unit, wherein the attachment portion includes an isolation member isolating the inside of the attachment portion into a first area in which a member for transmitting the drive force generated by the rotational drive unit to the shaft is rotatably held and a second area in which the catheter sheath is fixedly held; the isolation member includes: an insertion hole through which the shaft is inserted between the first area and the second area and an ejection hole provided in a surface to which an end portion on the rotational drive unit side of the catheter sheath is connected and which is approximately perpendicular to the rotation axis of the shaft; and the ejection hole defines a flow path extending to the outside of the isolation member.