A magnetic head device includes terminal pads formed on a side surface of a magnetic head, the magnetic head being installed on the edge of one surface side of a base plate; and a flexible wiring board comprising a connection terminal portion connected to each of the terminal pads of the magnetic head, a wiring extension portion extended from the connection terminal portion, and an extension terminal portion extended from the wiring extension portion. Herein, the connection terminal portion is disposed on the one surface of the base plate adjacently to the terminal pads of the magnetic head on the base plate; the wiring extension portion is folded back toward the other surface side of the base plate; the extension terminal portion is mounted on the other surface of the base plate; and the connection terminal portion and each of the terminal pads of the magnetic head are electrically interconnected.