An optical screening device includes a box and a light source. The box includes two chambers. The first chamber includes an incident passageway made with an exit. The second chamber includes a reflection passageway made with an entrance and an exit. The light source is inserted in the first chamber and adapted for casting incident light onto a first face of an inspected object located out of the box through the exit of the incident passageway so that primary reflected light goes into the second chamber from the first face of the inspected object via the entrance of the reflection passageway and goes out of the second chamber through the exit of the reflection passageway. The entrance of the reflection passageway is made with small width to allow only the primary reflected light to enter the second chamber.