A semiconductor device which can efficiently perform reading of a weight coefficient and a product-sum operation is provided. The semiconductor device includes a product-sum operation circuit and a memory device. The product-sum operation circuit is formed using transistors formed on a semiconductor substrate, and a memory cell of the memory device is formed using an OS transistor provided to be stacked above the semiconductor substrate. The semiconductor device includes a plurality of product-sum operation units where the product-sum operation circuit and the memory cell of the memory device are electrically connected to each other. In each of the product-sum operation units, a weight coefficient stored in the memory cell can be read and a product-sum operation can be performed.