A catheter is disclosed with a priming hole for exhaust at a distal portion of the catheter, the priming hole being used when filling with a priming solution is performed, and movably and rotatably accommodates an imaging core. The catheter includes a first connector that is provided at a rear end portion of the catheter and is supported by a fixed connector portion of a motor drive unit included in an imaging apparatus for diagnosis and a second connector that is supported by a movable connector portion of the motor drive unit. The catheter includes a reservoir, which is provided in the first connector and has a volume which decreases depending on a pull-out length of the second connector from the first connector, and a supply route, through which a priming solution injected from a priming injection port is supplied to the reservoir.