1. An imaging device comprising: a first unit including a first transfer transistor, a second transfer transistor and a first color filter disposed at a light-incident side of the first transfer transistor and the second transfer transistor; a second unit including a third transfer transistor, a fourth transfer transistor and a second color filter disposed at a light-incident side of the third transfer transistor and the fourth transfer transistor; a third unit including a fifth transfer transistor, a sixth transfer transistor and a third color filter disposed at a light-incident side of the fifth transfer transistor and the sixth transfer transistor; a fourth unit including a seventh transfer transistor, an eighth transfer transistor and a fourth color filter disposed at a light-incident side of the seventh transfer transistor and the eighth transfer transistor, wherein the first transfer transistor, the second transfer transistor, the third transfer transistor, the fourth transfer transistor, the fifth transfer transistor, the sixth transfer transistor, the seventh transfer transistor and the eighth transfer transistor are arranged in order along a horizontal direction along a same pixel row; a first transfer control signal line extending along the horizontal direction and electrically connected to a gate of the first transfer transistor and a gate of the fifth transfer transistor; a second transfer control signal line extending along the horizontal direction and electrically connected to a gate of the second transfer transistor and a gate of the sixth transfer transistor; a third transfer control signal line extending along the horizontal direction and electrically connected to a gate of the third transfer transistor; a fourth transfer control signal line extending along the horizontal direction and electrically connected to a gate of the fourth transfer transistor; a fifth transfer control signal line extending along the horizontal direction and electrically connected to a gate of the seventh transfer transistor; and a sixth transfer control signal line extending along the horizontal direction and electrically connected to a gate of the eighth transfer transistor.