Abstract: A guide wire including a core shaft that has a distal end portion and a proximal end portion. The distal end portion includes a first region having a flat shape in cross section, and a second region having a circular shape in cross section and having flexural rigidity higher than that of the first region. The first region and the second region are provided in the distal end portion in the stated order from a most distal end side, and at least two or more sets of the first region and the second region are provided at the distal end portion. Flat directions of the respective first regions are all identical.