Time-resolved photoluminescence (TRPL) and photostability were studied for several core/shell-type semiconductor quantum dots (QDs) of CdTe/CdS, In(Zn)P/ZnS and CdZnS/ZnS using a TRPL microscopy at a single QD level, of which results were compared to that of CdSe/ZnS QD. The CdTe/CdS and In(Zn)P/ZnS QDs show unstable PL at a single QD level on both bare and polymer-coated glass covers lips, so that they mostly lose emissions within a few seconds. The CdZnS/ZnS QD shows better emission stability than those of the former two QDs, but still less stable than the case of the CdSe/ZnS.