A humidity sensor 10 with high assembling properties and environmental resistance comprises a detecting element 14 having electrodes 14a and 14b formed on a base, conducting wires 12 and 13 connected individually to the electrodes by means of resin conductors formed of an organic high-molecular resin having an electrically conductive material dispersed therein, and a holding member 11 of an organic high-molecular resin for holding the detecting element and the conducting wires. The holding member has a connecting aperture 11c through which junctions between the electrodes and the conducting wires are exposed.