To provide a device and a method for VSB-modulating a digital signal by multiplying a digital signal having a data symbol inputted at a specified rate by a specified equation, giving specified different sums to an obtained product, multiplexing/transmitting the sum of even/odd coefficient terms and obtaining a baseband signal having real part and an imaginary part.

The residual sideband wave modulator is provided with a baseband filter 10 having a multiplier 12 multiplying an input signal arriving at the rate of R1/T [cos(πi/2)-(πi/2)] and a transversal filter 14 receiving the output of the multiplier 12 and giving different sums of the even/odd coefficient terms. Furthermore, an adder 16 adding a DC offset terms to the sum of the even coefficient terms and a multplexer 18 which multiplexes and transmits the sum of the odd coefficient terms and the even coefficient term plus a DC offset terms and supplies the baseband signal having the real part ReSbb (kT) and the imaginary part ImSbb (kT), which are shown by the equation.