In a dryer, humidity of supply air in a supply path of a heat pump dryer unit is directly detected by a first humidity detection sensor, and humidity of exhaust air in a discharge path is directly detected by a second humidity detection sensor. The first and second humidity detection sensors are collectively installed at one place, and a first conduit or a second conduit that guides the supply air or the exhaust air to a position of the corresponding sensor is provided. The sensors may be collectively disposed at one place in the supply path or the discharge path. This facilitates mounting of the sensor and saves a mounting space. Because environment temperatures of the two humidity sensors can be regarded as equal to each other when using relative humidity sensors, temperature detection for conversion into absolute humidity can be performed at one place.