This paper deals with measurement of the shielding effectiveness against the electromagnetic field. Shielding effectiveness against the electromagnetic field characterizes property of material to penetrate the electromagnetic field. Measuring of shielding effectiveness was performed in the frequency range from 1 GHz to 9 GHz with a step of 0.2 GHz. Measurement was performed in non-reflection chamber. Measured objects were the construction materials: Styrodur polystyrene with thickness of 50 mm, Styrodur polystyrene with thickness of 25 mm and their combination. The result of measurement is comparation of shielding effectiveness of shielding objects.