The present invention relates to microparticles containing finasteride, as microparticles containing finasteride and a biodegradable polymer, in a form in which the microparticles have a shape in which the finasteride drug is uniformly distributed in spherical biodegradable polymer particles, and the microparticles have an average particle diameter of 20 to 70 μm.The present invention relates to sustained-release microparticles which can maintain the effect of treating alopecia sustainably for 1 month to 3 months as the microparticles containing finasteride are administered, and a preparation method thereof, andthe present invention may facilitate storage and handling of microparticles containing finasteride unlike oral dosage forms as a patient need not directly store and handle the microparticles by using the microparticles containing finasteride in a manner that the microparticles are administered to the patient through injection, maintain the drug effect for a long period of time such as 1 month to 3 months, and facilitate the administration as an injection by decreasing a foreign body sensation and pain at the time of administering the injection to a patient as the particles are prepared to have the average diameter of the particles to a certain micro size.
