Provided are a coefficient multiplier and digital delta-sigma modulator using the same. The coefficient multiplier has the average of output signals of respective dependent multipliers as an effective coefficient using a coefficient averaging technique without employing an adder that has a complex structure and occupies a large chip area. Accordingly, the coefficient multiplier has a simple hardware constitution and small chip area in comparison with a canonical signed digit (CSD) coefficient multiplier, and the digital delta-sigma modulator employing the coefficient multiplier has a simple structure and small size.