US Patent 6884225 Medical guide wire

In a medical guide wire (1), a rigid portion (4A) is located at a distal end of a helical spring (4), and the rigid portion (4A) measures 0.5 mm or less which extends from a top end of a head plug (5) to a rear end of a portion in which the helical spring (4) is secured to the head plug (5), and an intermediary location (11) is secured to an intermediary boss portion (9) of a core line (3) to provide a loosely wound portion (8) from a rear end of the head plug (5) to the intermediary location (11) to be elastically expandable due to a clearence (C) appeared between line element turns of the loosely wound portion (8).