The present invention relates to a sustained-release injectable preparation comprising biodegradable polymer microspheres containing donepezil as an active ingredient, and a method for producing the same, and a sustained-release preparation of donepezil sustained-release microspheres having a high content of donepezil and a method for producing the same. It is possible to maximize the therapeutic effect by decreasing gastrointestinal side effects frequently encountered in conventional oral administration agents and increasing patients' compliance of medicines.
