A thermally assisted magnetic head has a slider having a medium-facing surface, and a light source unit having a light source support substrate, and a light source disposed on the light source support substrate; the slider has a slider substrate and a magnetic head portion disposed on a side surface of the slider substrate; the magnetic head portion has a magnetic recording element for generating a magnetic field, first and second waveguides, for receiving light through an end face and guiding the light to the medium-facing surface, and a near-field light generator disposed on an end face; the light source support substrate is fixed to a surface of the slider substrate so that light emitted from the light source can enter the end face of the first waveguide.