The objective of the invention is to provide a class D amplifier that can reduce aliasing noise. The class D amplifier has D/A converter 10 that operates at the first sampling frequency, and PWM driver 3 that receives the output from D/A converter 10. Said PWM driver 3 operates at the second sampling frequency synchronized to the first sampling frequency. The second sampling frequency can be correlated to the delta wave frequency of the PWM driver. Also, synchronization of said first sampling frequency and said second sampling frequency can be carried out with one of said frequencies being an integer multiple of the other.