A shaft (12) of a catheter (10A) has a thin portion (24) which constitutes a distal side of the shaft, a thick portion (26) which is provided further on a proximal side than the thin portion (24), and a tapered portion (28) which is provided between the thin portion (24) and the thick portion (26). The tapered portion (28) is formed more flexibly than the thick portion (26). The thick portion (26) has a first thick portion (38) and a second thick portion (39) which is provided between the tapered portion (28) and the first thick portion (38). The second thick portion (39) has a smaller outer diameter than the outer diameter of a proximal end of the tapered portion (28) and the outer diameter of the first thick portion (38), and is formed more flexibly than the first thick portion (38) .
