A pixel array has a plurality of output units arranged in matrix form and a plurality of A/D conversion units corresponds to the output units. Each of the output units outputs an electric signal based on incident electromagnetic waves. Each of the A/D conversion units converts the electric signal input from the corresponding output unit to a digital signal. A plurality of storage units corresponds to columns of the output units. Each of the storage units holds the corresponding digital signal. A first signal line is configured to supply a driving bias to at least one of the output units and the A/D conversion units. A second signal line is configured to transmit the digital signal from the A/D conversion units to the storage units. The output units are provided between the first signal line and the second signal line.