Abstract: An encoding device and method of using a bit rate control method which accurately predicts a target bit amount, provides excellent quality, and is applicable to a real-time environment through a simple mechanism, and a multimedia apparatus including the encoding device. The encoding device includes a group-of-pictures (GOP)-based bit assigning unit for assigning a GOP-based bit amount targetGOP, a macroblock-based bit assigning unit for assigning a macroblock-based bit amount for all macroblocks included in the GOP, a quantizing device for checking a current buffer state, determining a quantization parameter (QP) by using an alternating current (AC) coefficient obtained by transforming a macroblock if a buffer occupancy rate is lower than a predetermined limit rate, and performing quantization by using the determined QP, and a variable length coding (VLC) unit for performing VLC.