PURPOSE: To obtain an antimicrobial agent for foods, capable of exhibiting high sterilizing effect in a low concentration and short time, not changing sterilizing effect by pH, useful for sterilization of egg having shell due to flash washing, immersion, showering, etc., by using an aqueous solution containing chlorine dioxide.

CONSTITUTION: An aqueous solution of chlorine dioxide obtained from a chlorine dioxide generator and having 100ppm (mg/l) chlorine dioxide concentration is diluted using city water to provide the objective antimicrobial agent for foods, having 0.5-50ppm (mg/l) concentration of chlorine dioxide in an aqueous solution, exhibiting high sterilizing effect in a low concentration and short time, having wide sterilizing spectrum, not changing sterilizing effect by pH and extremely slightly in harmful by-products such as carcinogenic trihalomethane produced by reacting with organic substances in water, compared with that of sodium hypochlorite. Furthermore, the egg having shell can efficiently be sterilized by bringing the shell surface of the egg having shell into contact with an antimicrobial agent for foods comprising an aqueous solution containing chlorine dioxide for 1-500sec by a method of brush washing, immersing, showering, etc.