The present invention relates to an oral film preparation obtained by spreading a solution containing a high potency drug and a film-forming polymer and then drying the solution, and a method for preparing an oral film preparation containing a high potency drug, said method comprising spreading a solution containing the high potency drug and a film-forming polymer and then drying the same, and a package obtained by (a) packaging the oral film preparation in a packaging material and, after nitrogen substitution, sealing the packaging material, and/or (b) sealing the oral film preparation together with a deoxidant in a packaging material. Provided are an oral film preparation that contains a high potency drug and has excellent content uniformity, a method for easily preparing an oral film preparation that contains a high potency drug and has excellent content uniformity, and a highly stable package that contains the oral film preparation.