Provided is a core wire for guide wire in which high rigidity can be attained even with a fine wire diameter so that pushability is improved while the core wire is prevented from fatigue deformation, and a method for manufacturing the core wire.This core wire 15 for guide wire is made of a Ti-Ni based alloy and has a wire diameter not larger than 0.5 mm and a Youngs modulus not lower than 50 GPa. According to the manufacturing method, first, wire drawing is performed on a raw material M0 so that the raw material M0 is passed through a wire drawing dice 2 to be drawn to a certain length while the wire diameter of the core wire is reduced. Thus, a primary processed material M1 is formed. After that, the primary processed material M1 is hammered and drawn by swaging dices 5 and 5 so that a secondary processed material M2 is formed. In this manner, the core wire 15 having a wire diameter not larger than 0.5 mm and a Youngs modulus not lower than 50 GPa is manufactured.
