On the staphylococci which was divided from the impetigo contagiosa, the author examined the sensitibity and resistance of penicillin. 1) The penicillin sensitibity of the staphylococci is comparatively high, that is, 0.01-0.08 u/cc is 25.0%, 0.16-0.64 u/cc is 41.7%, and L. 28-20.48 u/cc is 33.3%. 2) The penicillin resistance of staphylococci in vivo was recognized 2 among 16 cases. 3) The resistance and recovery of staphylococci to penicillin was recognized in vitro. 4) The permeability of penicillin in vesicles and pustules are good, but their level are not enough for staphylococci of higher sensitivity.