Annular sustained release preparation and production method thereof

An annular sustained release preparation comprising:

• at least two polymer tubes having both ends sealed and integrated by pressure-welding, or at least one polymer tube and at least one polymer rod sealed and integrated at both ends by pressure-welding;
• and
• a sex pheromone liquid contained by at least one of the tubes or the tube;
• wherein an annular space can be formed by pulling the tubes or the tube and the rod apart from each other at a center portion therebetween, the center portion not having been pressure-welded;
• and an angle formed between 1) a line connecting respective centers of diameters of the tubes welded to each other or the tube and the rod welded to each other and 2) a direction of pressure applied by a pressure-welder for the pressure-welding is from 0 to 45° with respect to the line connecting respective centers of diameters of the tubes welded to each other or the tube and the rod welded to each other.