To provide an A/D converting circuit capable of improving an S/N ratio regardless of a color television system. An over-sampling A/D converting circuit according to an embodiment of the present invention includes: an A/D converter for over-sampling an analog video signal; a digital low-pass filter allowing passage of a signal component in a predetermined passing band out of the over-sampled signal; a down-sampling circuit for down-sampling the passed signal; and a color television system determining circuit for switching the passing band.