A catheter according to an aspect of the present invention comprises a flexible tubular insert section having, in the outer surface of the distal end side of the insert section, a plurality of notches arranged in the longitudinal direction of the insert section on one side of a plane passing through the longitudinal axis of the insert section, an operating wire passed through the insert section and capable of advancing or retreating to bend the distal end side of the insert section having the notches, and a reinforcing tube put on the insert section to cover substantially the overall length of the whole region of the insert section, except the distal end side of the insert section on which the notches are formed, and to restrain longitudinal compression of the insert section.