A solid-state imaging device includes: a first substrate; a second substrate; a pixel unit in which pixels are disposed in a matrix; and an A/D conversion unit that is disposed for every columns of the pixels and counts a count clock for only a period according to a magnitude of the pixel signal. The A/D conversion unit includes: counter units that is provided in one of the first substrate and the second substrate and generates n-bit count signals; memory units that is provided in the other of the first substrate and the second substrate and holds the count signals and outputs the held count signals to horizontal signal transfer lines; and a connection unit that connects each counter unit to a corresponding one of the memory units and simultaneously transfer the count signals from at least two counter units to at least two memory units.