Thermally stimulated depolarization current (TSDC) of acceptor (Mg)-doped BaTiO3 ceramics was analyzed with different acceptor concentrations for coarse-grained specimens with uniform grain sizes. In all specimens, the increase of the polarization temperature (T-P) for a fixed condition of polarization field (E-P) and polarization time (t(P)) increased TSDC peak associated with an oxygen vacancy (V-O(center dot center dot)) relaxation. When the acceptor concentration is increased, both T-P to generate same magnitude of TSDC and the relaxation temperature (T-m) of the TSDC peak systematically decreased. On the other hand, the activation energy of the oxygen vacancy relaxation showed roughly constant values of similar to 0.9 eV, irrespective of acceptor concentration. Such behavior can be explained by a decrease in the relaxation time constant (tau(0)), which is in turn associated with the shape of oxygen vacancy profile in the specimen after polarization. The decrease of T-P, T-m, tau(0), and the little change of activation energy from the TSDC data with the increase of acceptor concentration implies an increase in the oxygen vacancy concentration C(V-O(center dot center dot)). The experimentally observed behavior of C(V-O(center dot center dot)) vs acceptor concentration could be explained by the defect chemical model, and from these results, the acceptor ionization energy E-A was estimated to be about 1.0 eV.