A solid-state imaging device includes: a first semiconductor substrate including a photoelectric conversion element; and a second semiconductor substrate including at least a part of a peripheral circuit arranged in a main face of the second semiconductor substrate, the peripheral circuit generating a signal based on the charge of the photoelectric conversion element, a main face of the first semiconductor substrate and the main face of the second semiconductor substrate being opposed to each other with sandwiching a wiring structure therebetween; a pad to be connected to an external terminal; and a protection circuit electrically connected to the pad and to the peripheral circuit, wherein the protection circuit is arranged in the main face of the second semiconductor substrate.