A foldable and overlappable carrier box includes a base panel, a pair of first side panels erected along any two facing edges of the base panel, and a pair of second side panels erected along remaining facing edges of the base panel. Each of the first side panels is divided into an upper face and a lower face along a horizontal line, the upper face being foldable downwards, and each of the second side panels is divided into an upper portion and a lower portion along a horizontal line, so that when carrier boxes are stacked in multiple layers by folding the upper face, a lower portion of a carrier box located at an upper position is overlappable with an upper portion of a carrier box located at a lower position.