The present invention relates to a method for manufacturing uniform size polymeric nanoparticles containing poorly soluble drugs, and more particularly, to a method for manufacturing uniform size polymeric nanoparticles containing poorly soluble drugs, including a first step of dissolving a biodegradable polymer in a non-volatile polar organic solvent, a second step of adding poorly soluble drugs to water and the biodegradable polymer solution to produce a dispersion, and a third step of adding the dispersion to emulsifier solutions in a batch under the condition of low mechanical energy level stirring. The polymeric nanoparticles of the present invention is capable of manufacturing nano-sized small and uniform polymeric nanoparticles through a simple method of employing a non-volatile polar solvent, especially a solvent having a polarity similar to that of water, as a solvent for a mixture solution of biodegradable polymer and poorly soluble materials, and using a low mechanical energy condition and batch-adding of dispersion in an emulsifying process. The polymeric nanoparticles of the present invention are advantageous in that the dissolution rate of the poorly soluble drugs contained in polymeric particles is dramatically improved, and the poorly soluble drugs are gradually and steadily released and maintained at a constant density over a long period of time.