A nasal dilator (Nozovent) has been developed to fit in the nasal cavity and external nose of Caucasians, and beneficial effects have been confirmed. However, the ability of the device to dilate nasal valve areas of Orientals, whose external nose structure differs from that of Caucasians, has not been studied. We studied the effectiveness of the Nozovent device in preventing snoring and sleep apnea in Japanese subjects according to the methods described by Petruson. When the Nozovent device was worn by the eighteen subjects who experienced snoring, nine showed significant improvement, four showed good improvement, two fair improvement, and three discontinued the trial; the rate of improvement was 72.2%. The device was also seen to be effective for three patients with sleep apnea. The Nozovent device provides a unique method for non-surgical treatment of snoring, and the effectiveness is a result of dilatation of the nasal valve area. The principle is medically sound, and is equally applicable to nasal valves of both Caucasians and Japanese who have different external nose structures.