A humidity detection device includes a humidity sensor, a resistor connected to one-side of the humidity sensor, a first switching part connected to the resistor; a diode connected to the first switching part; a second switching part connected to the other-side of the humidity sensor, a potential difference generating part connected to the second switching part, a power supply supplying a voltage, and a control part applying the voltage as an alternating voltage to the humidity sensor by controlling the first switching part and the second switching part. The control part applies a current to the diode, the resistor and the humidity sensor in a first direction by connecting the second switching part to the ground, and applies the current to the resistor and the humidity sensor in a second direction, which is an opposite direction from the first direction, by connecting the first switching part to the ground.