PROBLEM TO BE SOLVED: To detect moisture content with high accuracy without crushing an inspection object.SOLUTION: A rotary shutter externally inserted into a predetermined amount case in which a capacitance type sensor is fitted so as to face a housing space can take a receiving position for allowing an upper opening to be opened to the outside through a receiving opening formed in the rotary shutter while closing a lower opening of the housing space around an axis of rotation by being operatively rotated by an electric motor, a predetermined amount holding position for closing both of the upper opening and the lower opening, and a discharging position for opening the lower opening to the outside through a discharging opening formed in the rotary shutter while closing the upper opening.
