The present invention relates to a composition for parenteral administration, containing donepezil as an active ingredient, and a preparation method therefor. Donepezil, which has been conventionally used for oral or transdermal administration, is prepared as microparticles comprising a biodegradable and biocompatible polymer and a release controller so as to be provided as a pharmaceutical composition for sustained release parenteral administration, thereby enabling in vivo sustained release continuously for 2-12 weeks or more. Therefore, it is possible to reduce the frequency of administration to a patient and maintain an effective concentration in the blood for a long time.
