PURPOSE: To detect 0W100% relative humidity and gaseous alcohol selectively with high sensitivity by an apatic ceramic material and a composite oxide of titanium and niobium between the separating electrodes provided to an element substrate consisting of said ceramic material.

CONSTITUTION: The 1st, the 2nd electrodes 2, 4 are provided via an apatite ceramics to an element substrate 1 consisting of an apatite ceramics. The 3rd electrode 3 is provided apart from the electrode 2 and a composite oxide 5 of titanium and niobium is provided between the electrodes 2, 3 in contact with the electrodes 2, 3. Thus, 0W100% relative humidity is detected with the substrate 1 and gaseous alcohol with the oxide 5 selectively with high sensitivity.