A valved catheter is provided which includes a slit that opens readily in both directions either when a fluid is caused to flow from the interior to the exterior thereof or when a fluid is caused to flow from the exterior to the interior thereof, and that prevents inadvertent closure thereof from the opened state. The valve includes an openable slit that penetrates from the inner surface to the outer surface of a distal end section of a valved catheter with a closed distal end, and edge portions on the two sides of the slit are formed along the direction in which the valved catheter extends. The slit includes a linear shape in the cross-section of the distal end section of the valved catheter that extends in a position away from a center line “c” that passes through the center of the valved catheter in parallel with this center line “c” whereupon, either one of the edge portions deforms more readily than either one of the other edge portions.
