As the first selection units 16 at the pixel 10 (1, 3), the pixel 10 (2, 3) and the pixel 10 (3, 3) in the third column enter an ON state, the source terminals of the amplifier units 15 in these three pixels 10 become electrically connected to the first vertical signal line VL1c. The electric current from the first electric current source 25c connected to the first vertical signal line VL1c is shunted and distributed to the pixel 10 (1, 3), the pixel 10 (2, 3) and the pixel 10 (3, 3) On the first vertical signal line VL1c, the pixel signals from the pixel 10 (1, 3), the pixel 10 (2, 3) and the pixel 10 (3, 3) are combined and a combined pixel signal is generated.