An electronic component mounting apparatus includes a beam projector for projecting a laser beam, a beam receiver which is placed in opposition to the beam projector and which receives a laser beam projected from the beam projector, a light-reception-sensitivity setting unit for adjusting light-reception sensitivity of the beam receiver, a projection-side orifice provided in the beam projector to narrow a projection spot diameter of the laser beam, and a reception-side orifice provided in the beam receiver to narrow a light-reception spot diameter, where the light-reception sensitivity of the beam receiver is improved. As a result, an electronic component mounting apparatus capable of accurately detecting height size of small components by using a relatively inexpensive photoelectric sensor can be provided.