Desmear treatment device and desmear treatment method

The present invention has as its object the provision of a desmear treatment device and a desmear treatment method capable of reliably performing a desmear treatment with high treatment efficiency. In the desmear treatment method of the present invention, when irradiating a to-be-treated object disposed in a treatment space with vacuum ultraviolet rays via an ultraviolet transmitting window member to remove smear in the to-be-treated object, a treatment gas containing active species to be activated by the irradiation of the vacuum ultraviolet rays and having contained moisture is supplied into the treatment space. The desmear treatment device includes treatment gas supply means having a humidifying mechanism for causing a treatment gas containing active species to be activated by vacuum ultraviolet rays from an ultraviolet light source to contain moisture.