There is provided a modulation circuit including a sampling unit that over-samples an input digital signal based on a multiplying clock signal, and outputs a first over-sampling signal, a first frequency conversion unit that outputs a first high-frequency signal based on the first over-sampling signal and a reference signal, a first filter unit that outputs a second high-frequency signal based on a second over-sampling signal obtained by delaying the first over-sampling signal by one clock and the reference signal, a second filter unit that outputs a third high-frequency signal based on a third over-sampling signal obtained by delaying the second over-sampling signal by one clock and the reference signal, and an adder unit that adds the first high-frequency signal, the second high-frequency signal, and the third high-frequency signal, and outputs an output signal.