A solid-state image sensing apparatus, comprising, a pixel portion, a conversion portion including a first group and a second group each of which includes at least one analog/digital conversion unit to convert an analog signal of the pixel portion into a digital signal, and a clock supply unit including a first clock buffer and a second clock buffer connected in series for propagation of a clock signal, wherein each of the analog/digital conversion units includes a comparison unit and a counter unit, the comparison unit compares the analog signal with a comparison reference potential, the counter unit measures a time from the start of the comparison to the change of the comparison result, each of the first clock buffer and the second clock buffer corrects a duty ratio of a clock signal by using a differential circuit.