Provided is an annular sustained release preparation to be used by opening a center portion thereof, the preparation having a strength enough to avoid cleaving at a welded end portion. More specifically, provided is 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 having both ends sealed and integrated 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 central portion not having been pressure-welded; and an angle formed between 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 the pressure application direction is from 0 to 45°.
