The present invention relates to covered porous biodegradable polymer microspheres for sustained-release drug delivery and tissue regeneration which has an interconnected inner open pore structure having a wide surface area and high porosity and an outer closed pore structure in which the surface of the microsphere is covered with a thin layer of a biodegradable polymer, and thereby the pores formed on the surface and exposed to the outside are closed; and methods for preparing the same. Due to such a characteristic pore structure, the covered porous biodegradable polymer microspheres according to the present invention can prevent the biologically active material from being excessively released in the early stage immediately after administration, and after that, can gradually release the biologically active material through the interconnected inner pore structure over a prolonged period as the biodegradable polymer thin layer is degraded. Therefore, the microsphere of the present invention can be effectively used for sustained-release drug delivery and tissue regeneration.