Pleural empyema is a rare and serious complication of pneumonia. Although it is frequently seen in children, there are only a few reports about pleural empyema in newborn infants. Here we report a case of early onset neonatal pneumonia complicated with pleural empyema. The causal microorganism was group A beta-hemolytic streptococci (GAS or Streptococcus pyogenes) presumably originating from the mother, who had a puerperal infection. The mother had fever, pelvic pain, and abnormal vaginal discharge two days after delivery and subsequent increase in the antistreptolysin O titer, suggesting streptococcus infection. The patient was successfully treated by pleural drainage in addition to synergistic antimicrobial therapy.