Self-assembled CdSe quantum dots have been fabricated by means of an alternate molecular beam supply. For the CdSe dot embedded in ZnSe and annealed at the growth temperature (250 o C), the PL peak showed a blueshift with increase of the annealing period. This denotes that the size of embedded CdSe dots becomes small by the alloy formation with the surrounding ZnSe. The bare CdSe dots exposed to vacuum (without any molecular beam irradiation) evaporate, and the CdSe dots gradually changed to ZnCdSe dots. It was confirmed that the ZnCdSe dots were stable compared with pure CdSe dots.