A grasping forceps 1 includes: a pair of guide sections 7A and 7B that guide maneuvering wires 6A and 6B in a direction of an axial line C of a sheath； an extending-and-retracting member (transmission section) 8 that transmits displacement information of the maneuvering section to the maneuvering wires 6A and 6B and outputs the displacement information to the intervention instrument； a distal direction movement inhibitor section (specific directional movement-inhibitor section) 10 that allows the sheaths of the maneuvering wires 6A and 6B toward the distal end； a proximal direction movement inhibitor section (specific directional movement-inhibitor section) 11 that allows the sheaths of the maneuvering wires 6A and 6B toward the distal end； and an locked-state-releasing section 12 that releases an engaging state of the guide sections 7A and 7B with the distal direction movement inhibitor section 10 or the proximal direction movement inhibitor section 11 based on the displacement input by the maneuvering section. Accordingly, an medical intervention instrument can be provided that can maintain a certain attitude of the intervention instrument once established during intervention even if an external force is applied, and that can carry out identical operations simultaneously, i.e., manipulating of the intervention instrument and releasing of a certain attitude of the intervention instrument.
