Disclosed is a donepezil-containing transdermally absorbable preparation which develops reduced adverse side effects and shows a satisfactory level of therapeutic effect. The preparation comprises an adhesive and a donepezil component (containing crystalline donepezil having type-B crystal polymorphism) and/or a salt thereof, wherein the donepezil component or the salt thereof is contained in an amount of 9 to 50% by mass relative to the total weight of the adhesive. The preparation (particularly, one having a non-aqueous adhesive layer) shows an excellent penetration of donepezil and/or a salt thereof into the skin, retains good stability of the active ingredient therein, and is remarkably reduced in local stimulation and adverse side effects.
