The present invention is to provide an A/D conversion device, a solid-state image-capturing device, and an electronic device capable of removing fixed pattern noise, capable of preventing an image from being corrupted, capable of generating an appropriate carry signal during bit shift, and capable of avoiding bit inconsistency even when the frequency of the carry signal increases due to the bit shift. A reading unit includes a comparator configured to compare the analog signal potential with a reference signal of which slope is variable, a counter latch unit capable of AD conversion based on processing according to the output of the comparator, and a bit shift function unit capable of bit-shifting the digital data obtained by the counter latch unit, and when digital Correlated Double Sampling (CDS) is performed with a first signal and a second signal having different bit precisions obtained from the comparison with reference signals of different slopes, the bit shift function unit bit-shifts the first signal or the second signal.