PROBLEM TO BE SOLVED: To prepare an anti-fogging agent hardly causing repelling and fluid dripping and capable of showing excellent spreadability by incorporating colloidal alumina, colloidal silica, polyethylene oxide or the like in a specific content ratio. SOLUTION: This anti-fogging agent is prepared by incorporating (A) colloidal alumina, (B) colloidal silica and (C) at least one of (i) polyethylene oxide having 25,000-1,000,000 weight average molecular weight, (ii) polyethylene glycol having 9.000-25,000 weight average molecular weight and (iii) an ethoxyalcohol of formula I [wherein, (m) and (n) are each 10-50] under a condition meeting formula II and III [A]-[C] are pts.wt. of the ingredients A-C, respectively}. The particle diameters of the ingredients A and B preferably are each <=0.1μm average primary particle diameter. The anti-fogging agent is applied in such as state that the ingredients A-C are dispersed in medium and has a viscosity of preferably 10-100 mPa.s when in application. The application of the anti-fogging agent can provide excellent agricultural film.
