This invention provides a method for producing semiconductor nanoparticles having a monodispersed distribution of particle sizes and the semiconductor nanoparticles produced by the same, which were insufficient in conventional reversed micelle methods. This method for producing semiconductor nanoparticles comprises steps of: forming semiconductor nanoparticles in the reaction field in the micelle or in the reversed micelle; and regulating the particle size of the semiconductor nanoparticles by size-selective photoetching, wherein the reaction field in the micelle or in the reversed micelle serves also as the dissolution field for ions that are produced when the semiconductor nanoparticles are subjected to size-selective photoetching. In this method, particle sizes of the semiconductor nanoparticles are regulated by adjusting the size of the dissolution field for ions and regulating the reactivity of size-selective photoetching.