A catheter comprising: an elongated flexible tubular main body; a plurality of manipulation wires (30, 30a, 30b) inserted through the tubular main body and having tips connected to a distal part of the tubular main body; a manipulation-part main body provided at a base end of the tubular main body; and a bending manipulation part having an engagement part engaging with base ends of the manipulation wires (30, 30a, 30b), and individually applying pulling force to the plurality of manipulation wires (30, 30a, 30b) through pulling operations so as to bend the distal part of the tubular main body, wherein the bending manipulation part is provided so as to be movable with respect to the manipulation-part main body, wherein the path lengths of the plurality of manipulation wires (30, 30a, 30b) from the tips thereof to the engagement part are simultaneously increased or decreased when the bending manipulation part and the manipulation-part main body move relative to each other, wherein the bending manipulation part is capable of transiting to a manipulation position or a retracted position with respect to the manipulation-part main body, wherein the path lengths when the bending manipulation part is at the retracted position are shorter than the path lengths when the bending manipulation part is at the manipulation position, wherein when the bending manipulation part at the manipulation position performs pulling manipulations, the pulling force is applied to the plurality of manipulation wires (30, 30a, 30b) and the distal part of the tubular main body is bent, wherein the bending manipulation part or the manipulation-part main body further comprises a transition restricting part, and the transition restricting part restricts the transition of the bending manipulation part from the manipulation position to the retracted position. an elongated flexible tubular main body; a plurality of manipulation wires (30, 30a, 30b) inserted through the tubular main body and having tips connected to a distal part of the tubular main body; a manipulation-part main body provided at a base end of the tubular main body; and a bending manipulation part having an engagement part engaging with base ends of the manipulation wires (30, 30a, 30b), and individually applying pulling force to the plurality of manipulation wires (30, 30a, 30b) through pulling operations so as to bend the distal part of the tubular main body, wherein the bending manipulation part is provided so as to be movable with respect to the manipulation-part main body, wherein the path lengths of the plurality of manipulation wires (30, 30a, 30b) from the tips thereof to the engagement part are simultaneously increased or decreased when the bending manipulation part and the manipulation-part main body move relative to each other, wherein the bending manipulation part is capable of transiting to a manipulation position or a retracted position with respect to the manipulation-part main body, wherein the path lengths when the bending manipulation part is at the retracted position are shorter than the path lengths when the bending manipulation part is at the manipulation position, wherein when the bending manipulation part at the manipulation position performs pulling manipulations, the pulling force is applied to the plurality of manipulation wires (30, 30a, 30b) and the distal part of the tubular main body is bent, wherein the bending manipulation part or the manipulation-part main body further comprises a transition restricting part, and the transition restricting part restricts the transition of the bending manipulation part from the manipulation position to the retracted position.