A catheter includes a main body; a first and a second lumen provided in the main body, wherein a first and a second guide wire are insertable in the first and second lumens, respectively; a first inclined surface provided, on a side of the center axis line, such that the first inclined surface is inclined frontward to approach the center axis line; a first opening formed in the first inclined surface and through which the first lumen opens outward; a second inclined surface provided, on the other side of the center axis line, such that the second inclined surface is inclined frontward to approach the center axis line; and a second opening formed in the second inclined surface and through which the second lumen opens outward.