Provided are a microcapsule emulsion which can release almost all the amount of a biological active substance comprised therein at a constant release rate over a prolonged period, and a method for producing the same. More specifically, provided is the microcapsule emulsion comprising an emulsion particle formed by emulsion polymerization of a total amount of 15 to 90 parts by weight of a first monofunctional alkyl (meth)acrylate ester and a first multifunctional (meth)acrylate ester in the presence of 100 parts by weight of a biological active substance; and a coated layer on the emulsion particle, the layer being formed by emulsion polymerization of a total amount of 20 to 200 parts by weight of a second monofunctional alkyl (meth)acrylate ester and a second multifunctional (meth)acrylate ester in the presence of the emulsion particle; wherein difference in carbon numbers between an alkyl group of the first monofunctional alkyl (meth)acrylate ester and an alkyl group of the second monofunctional alkyl (meth)acrylate ester is from 3 to 17.