Disclosed are a servo writer and a servo writing method capable of writing a servo signal onto a servo band of a magnetic tape in an excellent condition, regardless of the thickness of the magnetic tape. The strap includes a first end forming a neck section, a free end opposite the first end, and an intermediate section between the first end and the free end, the intermediate section having a predetermined width B1 and thickness T1 defining a predetermined cross-sectional area. Such properties include the ability to extract the polymerized medical devices with water. Processing is carried out to determine who is speaking by determining which person has his head in a position corresponding to the direction from which the sound came.