An imaging apparatus includes: pixel circuits (1) arranged in a matrix, each configured to generate a pixel signal by photoelectric conversion; readout circuits (50) each provided correspondingly to each column of the plurality of pixel circuits, and each configured to read out the pixel signals from the pixel circuits of a corresponding column; 2n first output lines (5-1 to 5-8) to which output terminals of every 2n columns of the readout circuits are commonly connected; and an adding unit configured to add the pixel signals from the pixel circuits arranged in different columns. Among the readout circuits on plural columns connected to the pixel circuits which are subjected to adding by the adding unit, only the readout circuit on one column performs the read out, and all of the 2n first output lines receives input of the pixel signals from one of the plural readout circuits.