A moisture detection sensor includes a resonant circuit composed of an antenna coil 53 and a capacitor C. A noncontact tag composed of covering materials 51 and 57 covers the resonant circuit. The capacitor C has a pair of electrodes 52 and 56 and a dielectric 55 interposed between the electrodes 52 and 56, and the covering material 57 contains a through-hole 57a that allows the liquid to infiltrate into the dielectric 55 from outside.