A humidifier for a wooden stringed instrument. The humidifier comprises a stiff, vapor-permeable tubular member having a cap attached to one end thereof. The humidifier is supported in a hole in the side wall of the stringed instrument, the stiffness of the tubular member allows the humidifier to be cantilevered within the sound box so that the tubular member does not contact the interior of the sound box. In a preferred embodiment, the humidifier is mounted in a hole extending through the string anchor insert of the instrument.