In a medical guide wire (1), a helical spring body (3) is made of austenitic stainless steel wire treated with a solid-solution procedure, and tightly drawn with a whole cross sectional reduction ratio as 90%-99.5%. A metallic wire (1a-1g) of the helical spring body (3) is heat treated at low temperature within a range in which a tensile rupture strength of the helical spring body (3) rapidly increases by partly or totally making use of a conductive heat generated when a core wire (2) and the helical spring body (3) are in part bonded by means of a welding member (4).This makes it possible to improve a mechanical strength property, especially a fatigue-resistant property against a repetitive bending action of the helical spring body (3).
