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°.
