Selection of the Lagrangian multiplier is a key factor to determine the performance of Rate-Distortion Optimization (RDO) in video coding. JM, reference S/W of H.264, employs only one RDO model for all macroblock. However, since the characteristics of macroblocks are different, RDO model adaptive to their characteristics can give some performance improvement. In this paper, we propose an RDO algorithm adaptive to characteristics of macroblocks. We empirically obtain the optimal Lagrangian multipliers considering characteristics of macroblocks. For performance evaluation, the proposed method is applied to JM10.2 and, as a result, we have PSNR gain of 0.2dB on average.