An actuating member for causing a flexible elongated member for medical use to perform a predetermined curving motion includes a push-pull member including a first moving part and a second moving part which are configured to be movable relative to one another in an axial direction of the elongated member, the first moving part and the second moving part being pushable and pullable so as to cause the elongated member to curve in the axial direction of the elongated member; a curving motion restricting member which is configured to be movable in the axial direction of the elongated member, and which is configured to restrict curving of at least a portion of the elongated member; and an operation member configured to operate movements of the first moving part, the second moving part, and the curving motion restricting member.