PURPOSE: To obtain an impregnating and coating agent containing a specific nitrogen atom-containing amphoteric surfactant and capable of preventing infection by viral disease may occur in contact of skin with a virus.

CONSTITUTION: The aimed agent contains a nitrogen atom-containing amphoteric surfactant selected from a carboxylic salt type amphoteric surfactant, sulfuric ester salt type amphoteric surfactant, sulfonate salt type amphoteric surfactant an phosphate salt type amphoteric surfactant, preferably alkyldi(aminoethyl) glycine salt or dialkyldiethylene triamino acetic acid salt as an active ingredient. The agent is used as a solution or paste having 0.0001W0.1wt.% concentration, preferably 0.001W0.01wt.% concentration and pH 4W9, preferably 6W8 and applied to contact position before contact of skin with a virus or before a virus invades inner human body before on after contact of skin with the virus.