To transfer a small number, we inherently need the small number of bits. But all bit lines on a data bus change their status and redundant power is consumed. To reduce the redundant power consumption, we introduce a concept named active bits. In this paper, we propose a power reduction scheme for data buses using the active bits. Suppressing switching activity of inactive bits, we can reduce redundant power consumption. We propose various power reduction techniques using active bits and the implementation methods. Experimental results illustrate 20% - 35% on average and up to 54.2% switching activity reduction.