Homo-and copolymers of poly(lactic acid) have gathered much attention because of their biodegradability and biocompatibility. They have numerous applications in the biomedical field due to their potential. In their polymers, we are interested in poly(lactic acid)-poly(ethylene glycol) block polymers. The amphiphilic triblock copolymers, poly(DL-lactic acid)-poly(ethylene glycol)-poly(DL-lactic acid)(PLEL), have known to be surface-active ability. Therefore, we have studied emulsification properties with the polymers. PLEL were prepared by ring-opening copolymerization of DL-lactide and poly(ethylene glycol) catalyzed by stannous 2-ethylhexanoate. We prepared ethyl acetate-water-PLEL emulsion and applied this emulsion to biodegradable polymer scaffolds. PLA scaffolds were prepared by an emulsion freeze-drying method. These scaffolds were made by varying water weight fraction. Their surface pore size became larger with increasing water weight fraction.