A solid-state imaging apparatus includes a plurality of pixels and an A/D converter for converting analog image signals from the pixels into digital signals including a higher digit bit and a lower digit bit in time series. The A/D converter includes a first holding unit for holding the higher digit bit of the digital signal, a second holding unit for holding the lower digit bit of the digital signal, a third holding unit for holding the digital signal from the first holding unit, and a fourth holding unit for holding the digital signal from the second holding unit. A first pair including the first and third holding units, and a second pair including the second and fourth holding units are arranged in a direction along the column of the two-dimensional array of pixels.