An image pickup apparatus of an embodiment includes pixel units each including a photoelectric conversion unit and an amplification transistor that outputs a signal based on an electric carrier generated by the photoelectric conversion unit, a first output line to which signals from first and other pixel units are output, and a second output line to which signals from second and other pixel units are output. A connection unit is arranged to control an electric connection between input nodes of the amplification transistors of the first and second pixel units is arranged. A control unit is arranged to selectively output a signal from at least one of the first and second pixel units to the first output line out of the first and second output lines when the connection unit mutually connects the input nodes of the first and second pixel units.