Provided is a toner which provides excellent balance between high temperature storage stability and low temperature fixability and which is less likely to cause the bleeding out of a release agent even in a long-term, high-temperature condition. Disclosed is a toner for developing electrostatic images, comprising: colored resin particles comprising a binder resin, a colorant and a release agent, and an external additive, wherein the colored resin particles further comprise a styrene-based thermoplastic elastomer, and wherein a content of a fatty acid ester compound having a number average molecular weight (Mn) of 500 or more and less than 2,000 as the release agent, is from 2 parts by mass to 20 parts by mass with respect to 100 parts by mass of the binder resin.