There is provided a head-gimbal-assembly for use in heat-assist magnetic recording, excellent in the heat-release characteristic of a laser diode, by inhibiting effects of deterioration in lateral balance, and wind turbulence without adversely affecting efforts to lower a profile of a magnetic disk unit. For this purpose, a sub-mount with a laser diode attached thereto is mounted on either of the right and left lateral faces of a head slider. Further, of two lengths of lead wires for power supply to the laser diode, one length of the lead wire is routed to a lateral face of the head-slider, on the opposite side of a lateral face with the sub-mount attached thereto, after circling around the outer periphery of a head-slider electrode, formed on the gas-outlet side of the head slider.