The field isolate of porcine epidemic diarrhea virus (PEDV) was serially passaged in Vero cells. The cell passaged PEDV, designated KPEDV-9, was tested for its pathogenicity in the neonatal pigs, immunogenicity and safety in the pregnant sows. The result indicated that KPEDV-9 at the 93rd passage revealed reduced pathogenicity in the neonatal pigs. Pregnant sows inoculated with the attenuated virus showed increased immune responses by ELISA. In addition, delivered piglets were protected from challenge of wild type PEDV. The safety test in pregnant sows indicated that all inoculated animals farrowed the average numbers of litters of piglets. The results of this study supported that the attenuated virus derived from serial passage could be applied as vaccine for protecting suckling piglets against PEDV infection.