Amphiphilic AB-type diblock copolymers composed of hydrophobic poly(L-lactide) (PLA) segments and hydrophilic poly(glycolic acid lysine) [poly(Glc-Lys)] segments with amino side-chain groups self-associated to form PLA-based polymeric micelles with amino surfaces in an aqueous solution. The average diameter of the loose core-shell polymeric micelles for poly(Glc-Lys) [number-average molecular weight (M-n) = 1240]-b-PLA (M-n = 7000) obtained by a dimethyl sulfoxide/water dialysis method was estimated to be about 50 nm in water by dynamic light scattering measurements. The size and shape of the obtained polymeric micelles were further observed with transmission electron microscopy and atomic force microscopy. To investigate the possibility of applying the obtained PLA-based polymeric micelles as bioabsorbable vehicles for hydrophobic drugs, we tested the entrapment of drugs in poly(Glc-Lys) (M-n = 1240)-b-PLA (M-n = 7000) micelles and their release with doxorubicin as a hydrophobic drug.