The purpose of this study was to investigate to potective effects against porcine epidemic diarrhea virus (PEDV) infection in piglets by administration of the PEDV antiserum orally at 2 hrs, 24hrs and 36hrs after birth. six piglets administered the antiserum were experimentally infected with PEDV at five-day-old. Control group were four piglets infected with PEDV only. Serum antibody titers against PEDV were examined by serum neutralization (SN) test, dectection for PEDV or PEDV antigen from feces and small intestines was tested by reverse transcription-polymerase chain reaction (RT-PCR) and indirect immunoflurescence (IFA). The results obtained were as follows; 1. The piglets administered the PEDV antiserum showed higher antibody titers than those of control group and sustained during the experimental period. 2. The detection rate of PEDV in feces and small intestines by RT-PCR were 26.2% and 16.7% in PEDV antiserum treated group and 48.1 % and 75.0% in control group, respectively. 3. The detection rate of PEDV antigen in the small intestine by IFA were 0% in PEDV antiserum treated group and 50.0% in control group, respectively. It was concluded that oral administration of antiserum against PEDV to piglets was effective in preventing PEDV infection.