A guide wire comprising: a flexible core wire, the core wire comprising: a distal core portion that includes a foremost distal end and is most flexible in an entire length of the core wire; a main body portion that constitutes a portion more proximal than the distal core portion and has a constant diameter along an axial direction; and a rigidity changing portion that constitutes a portion from a distal end of the main body portion to a proximal end of the distal core portion and gradually decreases in rigidity from the main body portion toward the distal core portion, the rigidity changing portion comprising at least: a first tapered portion that is continuous with the distal end of the main body portion and has a diameter gradually decreasing from the main body portion toward the distal core portion; a second tapered portion that is continuous with a distal end of the first tapered portion and has a diameter gradually decreasing from the first tapered portion toward the distal core portion; and an n-th tapered portion that is continuous with the proximal end of the distal core portion and has a diameter (dn) gradually decreasing from an (n-1)th tapered portion being continuous with the proximal side toward the distal core portion (wherein, n ≥ 3), wherein a boundary portion between the first tapered portion and the second tapered portion is located in a range of 300 to 400 mm from the foremost distal end of the distal core portion, and characterized in that a gradient ((d12 - d11)/L1) of a change in the diameter in the first tapered portion is larger than a gradient ((d22 - d21)/L2) of a change in the diameter in the second tapered portion. a flexible core wire, the core wire comprising: a distal core portion that includes a foremost distal end and is most flexible in an entire length of the core wire; a main body portion that constitutes a portion more proximal than the distal core portion and has a constant diameter along an axial direction; and a rigidity changing portion that constitutes a portion from a distal end of the main body portion to a proximal end of the distal core portion and gradually decreases in rigidity from the main body portion toward the distal core portion, a distal core portion that includes a foremost distal end and is most flexible in an entire length of the core wire; a main body portion that constitutes a portion more proximal than the distal core portion and has a constant diameter along an axial direction; and a rigidity changing portion that constitutes a portion from a distal end of the main body portion to a proximal end of the distal core portion and gradually decreases in rigidity from the main body portion toward the distal core portion, the rigidity changing portion comprising at least: a first tapered portion that is continuous with the distal end of the main body portion and has a diameter gradually decreasing from the main body portion toward the distal core portion; a second tapered portion that is continuous with a distal end of the first tapered portion and has a diameter gradually decreasing from the first tapered portion toward the distal core portion; and an n-th tapered portion that is continuous with the proximal end of the distal core portion and has a diameter (dn) gradually decreasing from an (n-1)th tapered portion being continuous with the proximal side toward the distal core portion (wherein, n ≥ 3), wherein a first tapered portion that is continuous with the distal end of the main body portion and has a diameter gradually decreasing from the main body portion toward the distal core portion; a second tapered portion that is continuous with a distal end of the first tapered portion and has a diameter gradually decreasing from the first tapered portion toward the distal core portion; and an n-th tapered portion that is continuous with the proximal end of the distal core portion and has a diameter (dn) gradually decreasing from an (n-1)th tapered portion being continuous with the proximal side toward the distal core portion (wherein, n ≥ 3), wherein a boundary portion between the first tapered portion and the second tapered portion is located in a range of 300 to 400 mm from the foremost distal end of the distal core portion, and characterized in that a gradient ((d12 - d11)/L1) of a change in the diameter in the first tapered portion is larger than a gradient ((d22 - d21)/L2) of a change in the diameter in the second tapered portion.