PURPOSE:To easily detect dew condensation by arranging a conductor between a holed base sheet and a cover sheet. CONSTITUTION:A connecting hole 6 is bored in the base sheet 1 made of insulating resin. The conductor 3 is arranged on this base sheet 1 and covered with the resin-made cover sheet 2. A detection window 5 is formed in this cover sheet 2 so as to include the connecting hole 6 and conductor 3. Further, an adhesive sheet 4 is stuck on the reverse surface of the base sheet 1 to adhere a sensor 9 to a panel 7. Then a power source 8 is connected to the sensor 9 through a resistance 11 and the gate 10 of an IC is connected between the resistance 11 and sensor 9. Further, the panel 7 is grounded. When dew condensation starts on the surface of the panel 7, dew condensation occurs even on the surface of the base sheet 1 in the detection window 5 and the conductor 3 and panel 7 are short-circuited by drops of dew. A current flows owing to the short-circuiting and a voltage applied to the gate 10 of the IC falls to 0, so the dew condensation on the panel 7 can be detected.
