An aiming mechanism of a headlamp for an automobile, comprises: a lamp housing which is mounted on a vehicle body; a headlamp unit supported tiltably about a tilting fulcrum provided in front of the lamp housing; a hollow cylindrical nut member supported rotatably about an axis by a bearing provided in the lamp housing; and an aiming screw which is threadedly engaged with the nut member, extends forward, is prevented from rotating with respect to the headlamp unit, and is adapted to advance and retract in an axial direction to tilt the headlamp unit connected to a forward end thereof as the nut member is rotated, wherein a crown-shaped gear capable of meshing with teeth of a screwdriver disposed in a direction perpendicular to the aiming screw is formed integrally on the nut member, and at least two screwdriver guides for guiding the screwdriver are provided in vicinities of the bearing.