A modulating device including: a first convertor configured to generate a converted analog signal by analog conversion on a input digital signal, a modulator configured to generate a modulated signal by quadrature modulation, a phase shifter configured to generate a phase shift signal by phase rotation, a demodulator configured to generate a demodulated signal by quadrature demodulation, a second convertor to generate a converted digital signal by digital conversion, a calculating circuit configured to estimate a the first direct current offset based on the input digital signal and the converted digital signal, the first direct current offset being a noise of digital current component generated between the input digital signal inputted to the first convertor and the output signal inputted to the demodulator, and a correcting circuit configured to correct at least one among from the input digital signal to the output signal based on the first direct current offset.