A solid-state imaging device including two semiconductor substrates arranged in layers is provided. Each semiconductor substrate has a semiconductor region in which a circuit constituting a part of a pixel array is formed. The circuits in the two semiconductor substrates are electrically connected to each other. Each semiconductor substrate includes one or more contact plugs for supplying a voltage to the semiconductor region. The number of the contact plugs of one semiconductor substrate in the pixel array is different from the number of the contact plugs of the other semiconductor substrate in the pixel array.