Fractionated samples Of D,L-poly(lactic acid) (PLA) were prepared and the dielectric normal mode relaxation was studied for dilute and semi-dilute solutions of the PLA in a good solvent benzene. Results indicate that in the dilute regime the normal mode relaxation time is proportional to [eta]M-w in agreement with the Rouse-Zimm theory, where [eta] and M-w denote the intrinsic viscosity and weight average molecular weight, respectively. The dielectric relaxation strength which is proportional to the mean square end-to-end distance [r(2)] increases with increasing M-w with the power of 2nu, where nu is the excluded volume parameter determined from [eta]. The relaxation time in the semi-dilute regime increases with increasing concentration C due to increases of the entanglement density and the friction coefficient. The relaxation time corrected to the iso-friction state agrees approximately with the dynamic scaling theories. The relaxation strength decreases with increasing concentration indicating that [r(2)] decreases on account of the screening of the excluded volume effect. The concentration dependence of [r(2)] agrees approximately with the scaling theory proposed by Daoud and Jannink.