A branch blood vessel insertion catheter (1) is inserted into a small-diameter branch blood vessel branching from a first blood vessel. The catheter (1) has a catheter body (2) having a lumen (20) penetrating therethrough from a distal end thereof to a proximal end thereof to allow a guide wire (15) to be inserted therethrough. The catheter body (2) has an inner layer (3), a wire-wound reinforcing member (5) mounted on an outer surface of the inner layer (3), and an outer layer (4) covering both the inner layer (3) and the wire-wound reinforcing member (5). The catheter body (2) has a first physical property change point (6) located at a position apart from the distal end of the catheter body (2) at a distance of 3.0 to 7.0mm. The rigidity of a portion of the catheter body (2) located proximally from the first physical property change point (6) is set higher than that of a portion of the catheter body (2) located distally therefrom.
