A flexible wiring board for a magnetic head assembly is provided. The flexible wiring board includes a wiring pattern connected to a head body at one end and to an external circuit system at the other end, an insulation protection film that protects the wiring pattern, and a base composed of a metal that extends over the insulation protection film and the wiring pattern. The base has a guide through hole that functions as a guide for bending the base. The guide through hole has a plurality of notches disposed at different positions in a length direction of the base. The notches reduce a remaining width of the base in a bend width direction of the base.