A direct extraction method was developed for exosomal microRNAs. After isolation of exosomes from human serum by immunoaffinity magnetic beads, microRNAs were extracted by just mixing beads with a lysis solution and heating without further purification. The lysis solution was composed of a nonionic detergent and salt (NaCl). The concentration of each component was optimized to maximize lysis efficiency and to inhibit adsorption of extracted microRNAs on beads. MicroRNAs extracted by this method could be quantitatively analyzed by qRT-PCR, indicating that the method could replace conventional methods for extracting microRNAs from immunobead-captured exosomes.