A first tube (7) is a medical tube which is provided with a first site (71), a second site (72) and a third site (73) in this order from the proximal end side toward the distal end side and is made of a resin. At the second site (72), the outer diameter c thereof is smaller than the outer diameter a of the first site (71) and the inner diameter d is substantially equal to the inner diameter b of the first site (71), and at the third site (73), the outer diameter e and the inner diameter f thereof are respectively smaller than the outer diameter c and the inner diameter d of the second site (72). In this manner, a medical tube in which the outer diameter of the proximal end side is relatively large and the outer diameter of the distal end side is relatively small while securing the inner diameter having a sufficient size at the distal end side can be provided.
