A solid-state image pickup apparatus comprising: a pixel array including a plurality of pixels arranged in a number of columns, a plurality of output signal lines, and a column circuit block array including a plurality of column circuit blocks that are individually connected to the plurality of output signal lines, wherein the column circuit block array is configured to process signals output from the plurality of pixels in parallel wherein each pixel comprises: photoelectric converting means configured to generate electric charge; and first amplifying means configured to amplify a signal corresponding to an amount of the electric charge, and output a first amplified signal to the output signal line characterized in that each column circuit block comprises: storing means configured to temporarily store the first amplified signal; and second amplifying means configured to amplify the first amplified signal stored by the storing means, and output a second amplified signal to the output signal line, and the apparatus further comprises for each output signal line: a current source, connected to the output signal line, which is configured to be shared by the first and second amplifying means for supplying a driving current for each of the first amplifying means and the second amplifying means; and selecting means (105, 203, 700, 215) configured to control the first amplifying means and the second amplifying means to be in one of an active state for outputting the respective amplified signal and an inactive state for not outputting the respective amplified signal, respectively, such that the first amplifying means is in the active state while the second amplifying means is in the inactive state, and the first amplifying means is in the inactive state, while the second amplifying means is in the active state. a pixel array including a plurality of pixels arranged in a number of columns, a plurality of output signal lines, and a column circuit block array including a plurality of column circuit blocks that are individually connected to the plurality of output signal lines, wherein the column circuit block array is configured to process signals output from the plurality of pixels in parallel wherein each pixel comprises: photoelectric converting means configured to generate electric charge; and first amplifying means configured to amplify a signal corresponding to an amount of the electric charge, and output a first amplified signal to the output signal line characterized in that photoelectric converting means configured to generate electric charge; and first amplifying means configured to amplify a signal corresponding to an amount of the electric charge, and output a first amplified signal to the output signal line characterized in that each column circuit block comprises: storing means configured to temporarily store the first amplified signal; and second amplifying means configured to amplify the first amplified signal stored by the storing means, and output a second amplified signal to the output signal line, and storing means configured to temporarily store the first amplified signal; and second amplifying means configured to amplify the first amplified signal stored by the storing means, and output a second amplified signal to the output signal line, and the apparatus further comprises for each output signal line: a current source, connected to the output signal line, which is configured to be shared by the first and second amplifying means for supplying a driving current for each of the first amplifying means and the second amplifying means; and selecting means (105, 203, 700, 215) configured to control the first amplifying means and the second amplifying means to be in one of an active state for outputting the respective amplified signal and an inactive state for not outputting the respective amplified signal, respectively, such that the first amplifying means is in the active state while the second amplifying means is in the inactive state, and the first amplifying means is in the inactive state, while the second amplifying means is in the active state. a current source, connected to the output signal line, which is configured to be shared by the first and second amplifying means for supplying a driving current for each of the first amplifying means and the second amplifying means; and selecting means (105, 203, 700, 215) configured to control the first amplifying means and the second amplifying means to be in one of an active state for outputting the respective amplified signal and an inactive state for not outputting the respective amplified signal, respectively, such that the first amplifying means is in the active state while the second amplifying means is in the inactive state, and the first amplifying means is in the inactive state, while the second amplifying means is in the active state.