A sustained release pheromone preparation comprising: at least one pheromone substance, and a container for enclosing the pheromone substance therein, the container comprising a polymer membrane which comprises a polymer blend of: an aliphatic polyester having following structural units: wherein "a" and "1-a" mean compositional ratios of the structural units and "a" is the number which satisfies the equation: 0<a≤1, R 1 is one selected from divalent hydrocarbon groups having 1 to 8 carbon atoms, R 2 is one selected from divalent hydrocarbon groups having 1 to 7 carbon atoms, with the proviso that R 1 has more carbon atoms than R 2 does when "a" is not 1, m 1 and m 2 may be the same as or different from each other and each stands for a positive integer of from 2 to 10, and a poly(hydroxyalkanoate) having the following structural units: wherein "b" and "1-b" mean compositional ratios of the structural units and "b" is the number which satisfies the equation: 0<b<1, R 3 is one selected from a hydrogen atom and monovalent hydrocarbon groups having 1 to 4 carbon atoms, "n" stands for an integer of from 0 to 4, with the proviso that "n" is not 1 when R 3 is a methyl group, wherein the pheromone substance is selected from the group consisting of aliphatic alcohols having 10 to 18 carbon atoms, acetate esters of aliphatic alcohols having 10 to 18 carbon atoms, and aliphatic aldehydes having 10 to 18 carbon atoms. at least one pheromone substance, and a container for enclosing the pheromone substance therein, the container comprising a polymer membrane which comprises a polymer blend of: an aliphatic polyester having following structural units: wherein "a" and "1-a" mean compositional ratios of the structural units and "a" is the number which satisfies the equation: 0<a≤1, R 1 is one selected from divalent hydrocarbon groups having 1 to 8 carbon atoms, R 2 is one selected from divalent hydrocarbon groups having 1 to 7 carbon atoms, with the proviso that R 1 has more carbon atoms than R 2 does when "a" is not 1, m 1 and m 2 may be the same as or different from each other and each stands for a positive integer of from 2 to 10, and a poly(hydroxyalkanoate) having the following structural units: wherein "b" and "1-b" mean compositional ratios of the structural units and "b" is the number which satisfies the equation: 0<b<1, R 3 is one selected from a hydrogen atom and monovalent hydrocarbon groups having 1 to 4 carbon atoms, "n" stands for an integer of from 0 to 4, with the proviso that "n" is not 1 when R 3 is a methyl group, wherein the pheromone substance is selected from the group consisting of aliphatic alcohols having 10 to 18 carbon atoms, acetate esters of aliphatic alcohols having 10 to 18 carbon atoms, and aliphatic aldehydes having 10 to 18 carbon atoms. an aliphatic polyester having following structural units: wherein "a" and "1-a" mean compositional ratios of the structural units and "a" is the number which satisfies the equation: 0<a≤1, R 1 is one selected from divalent hydrocarbon groups having 1 to 8 carbon atoms, R 2 is one selected from divalent hydrocarbon groups having 1 to 7 carbon atoms, with the proviso that R 1 has more carbon atoms than R 2 does when "a" is not 1, m 1 and m 2 may be the same as or different from each other and each stands for a positive integer of from 2 to 10, and a poly(hydroxyalkanoate) having the following structural units: wherein "b" and "1-b" mean compositional ratios of the structural units and "b" is the number which satisfies the equation: 0<b<1, R 3 is one selected from a hydrogen atom and monovalent hydrocarbon groups having 1 to 4 carbon atoms, "n" stands for an integer of from 0 to 4, with the proviso that "n" is not 1 when R 3 is a methyl group, wherein the pheromone substance is selected from the group consisting of aliphatic alcohols having 10 to 18 carbon atoms, acetate esters of aliphatic alcohols having 10 to 18 carbon atoms, and aliphatic aldehydes having 10 to 18 carbon atoms. wherein "b" and "1-b" mean compositional ratios of the structural units and "b" is the number which satisfies the equation: 0<b<1, R 3 is one selected from a hydrogen atom and monovalent hydrocarbon groups having 1 to 4 carbon atoms, "n" stands for an integer of from 0 to 4, with the proviso that "n" is not 1 when R 3 is a methyl group, wherein the pheromone substance is selected from the group consisting of aliphatic alcohols having 10 to 18 carbon atoms, acetate esters of aliphatic alcohols having 10 to 18 carbon atoms, and aliphatic aldehydes having 10 to 18 carbon atoms.