A solid-state imaging apparatus, including a plurality of pixels, and an A/D conversion unit configured to convert a pixel signal of an analog signal into a digital signal, wherein the A/D conversion unit comprises a comparator, a sampling unit, a counter, and an output unit configured to output the digital signal based on a count result of the counter and a sampling result of the sampling unit, and the sampling unit comprises first and second latch units configured to latch an output from the comparator in response to first and second clock signals, respectively, and a third latch unit configured to latch an output from the first latch unit in response to an output of the second latch unit.