To obtain a bactericidal agent effectively acting to equipment, instruments in medical and food manufacturing floors or employees for the same even in the presence of organic materials.

This bactericidal agent is a water-based bactericidal agent and contains 1-10 weight/volume % isopropyl alcohol, 0.01-0.2 weight/volume % invert soap (benzalkonium chloride and the like) and 0.01-0.15 weight/volume % chlorine dioxide agent (a chlorite and the like). The bactericidal agent cleans and removes bloods, fats, proteins and the like even in the presence of them and effectively expresses bactericidal effect. Stimulation to fingers, the skin and the like is reduced. There is little fear of appearing resistant bacteria.