A catheter includes a first opening portion positioned at a distal end; a first curved portion positioned proximally of the first opening portion, and is curved in a first direction; a second curved portion positioned proximally of the first curved portion, and is curved in a second direction; an intermediate portion provided between the first curved portion and the second curved portion; and a second opening portion formed in the intermediate portion. In a transverse sectional view of the intermediate portion, the first direction and the second direction are directions directed towards a first side of the intermediate portion. In addition, in the transverse sectional view of the intermediate portion, the second opening portion opens in a third direction directed towards a second side of the intermediate portion that is opposite to the first side.