Abstract: A thermally assisted magnetic head comprises: a slider substrate, a first surface located opposite to a medium-facing surface, and side surfaces located between the medium-facing surface and the first surface; a magnetic head portion having a near-field light generator on the medium-facing surface side, and a magnetic recording element, the magnetic head portion being fixed to one of the side surfaces; and a laser diode element a relative position of which to the slider substrate is fixed so that emitted light thereof can reach the near-field light generator; a relation of ?in<?max is satisfied, where ?in is a wavelength of the emitted light from the laser diode element immediately before the emitted light reaches the near-field light generator, and ?max is a wavelength of irradiating light at which an efficiency of generation of near-field light generated from the near-field light generator is maximum.