Abstract: A catheter is provided whose distal end can be introduced through an artery in the arm into the entrance of the left coronary artery. The catheter includes a catheter body having an outer diameter of at most 2.7 mm over its entire length and has a proximal segment straight under a free state and a distal segment having a curved shape under a free state. The distal segment includes a first straight portion contiguous to the proximal segment through a first curved portion, a second straight portion contiguous to the first straight portion through a second curved portion bent in a direction opposite to the bending direction of the first curved portion, a third straight portion contiguous to the second straight portion through a third curved portion bent in the bending direction of the second curved portion, and a straight distal end portion contiguous to the third straight portion through a fourth curved portion bent in the bending direction of the third curved portion.