An XY-address solid-state image pickup apparatus comprises a pixel array made up a plurality of pixels two-dimensionally arranged and horizontal and vertical scanning circuits for reading the signal from the pixel array. Each scanning circuit comprises a plurality of unit stages cascaded, each unit stage comprising a plurality of first shift register units cascaded and a single second shift register unit which is associated with the plurality of first shift register units and which is driven by a clock different from the clock that drives the plurality of first shift register units. Each unit stage further comprises a first switch and a second switch. The input to the first unit of the first shift register units is also fed to the second shift register unit via the first switch. The output of the second shift register unit is fed to each of the plurality of first register units within the unit stage via the second switch. Each scanning circuit further comprises driving means for turning on/off the first and second switches in order to switch between a normal scanning and a thinned-out scanning.