A diagnostic imaging catheter is disclosed, which includes a sheath that is inserted into a body-cavity in a living body； an ultrasound transducer that is inserted into the sheath and is able to transmit and receive an ultrasound wave； a connector unit that is provided in a proximal portion of the sheath, an electrode terminal that is disposed inside the connector unit and is electrically connected to an external electrode terminal included in an external apparatus which transmits and receives an electrical signal with respect to the ultrasound transducer； a conductive member that is provided inside the connector unit, is electrically connected to a positive electrode and a negative electrode of the electrode terminal, and causes both the electrodes to be in a short-circuit state； and a switch unit that is configured to be able to cancel the short-circuit state of both the electrodes caused by the conductive member.
