The catheter provided in accordance with aspects of the present invention includes an elongate tube having a proximal tube portion and a distal tube portion formed by stretching the distal portion of the elongate tube. The catheter is made throughout from an identical material. The distal tube portion has a reduced outer diameter and thus is of a higher flexibility and softness. Therefore, the danger of injuries to vessels or the dura is decreased. The catheter can be produced in an inexpensive and simple manner.