A solid-state image pickup element comprising: a plurality of pixel circuits; and a control circuit controlling each of said pixel circuits, wherein each of said pixel circuits includes: a light detector element generating a signal charge in response to light reception; an accumulating region accumulating the signal charges generated by said light detector element; a floating diffusion region; a reset switch for electrically connecting a power supply node supplying a reset potential to said floating diffusion region in response to a reset signal; and a transfer circuit configured to transfer the signal charges in said accumulating region to said floating diffusion region when being operated, while being configured to stop said transfer when not being operated, wherein said control circuit is configured to control said transfer circuit of each said pixel circuit so as to operate said transfer circuit during a complete transfer period required for said transfer circuit to transfer a maximum signal charge accumulative quantity (Qpdmax) in said accumulating region from said accumulating region to said floating diffusion region, and so as to continue to operate said transfer circuit during a first period after the elapse of said complete transfer period, said maximum signal charge accumulative quantity is determined by capacitance value of said accumulating region, said control circuit further controls said reset switch so as to keep an electrically separated condition between said floating diffusion region and said power supply node while said transfer circuit is operated, and a capacitance value (Cfd) of said floating diffusion region is not less than a sum of a first capacitance value required to receive said maximum signal charge accumulative quantity, and a second capacitance value required to receive said signal charge generated by said light detector element during said first period. a plurality of pixel circuits; and a control circuit controlling each of said pixel circuits, wherein each of said pixel circuits includes: a light detector element generating a signal charge in response to light reception; an accumulating region accumulating the signal charges generated by said light detector element; a floating diffusion region; a reset switch for electrically connecting a power supply node supplying a reset potential to said floating diffusion region in response to a reset signal; and a transfer circuit configured to transfer the signal charges in said accumulating region to said floating diffusion region when being operated, while being configured to stop said transfer when not being operated, wherein said control circuit is configured to control said transfer circuit of each said pixel circuit so as to operate said transfer circuit during a complete transfer period required for said transfer circuit to transfer a maximum signal charge accumulative quantity (Qpdmax) in said accumulating region from said accumulating region to said floating diffusion region, and so as to continue to operate said transfer circuit during a first period after the elapse of said complete transfer period, said maximum signal charge accumulative quantity is determined by capacitance value of said accumulating region, said control circuit further controls said reset switch so as to keep an electrically separated condition between said floating diffusion region and said power supply node while said transfer circuit is operated, and a capacitance value (Cfd) of said floating diffusion region is not less than a sum of a first capacitance value required to receive said maximum signal charge accumulative quantity, and a second capacitance value required to receive said signal charge generated by said light detector element during said first period. a light detector element generating a signal charge in response to light reception; an accumulating region accumulating the signal charges generated by said light detector element; a floating diffusion region; a reset switch for electrically connecting a power supply node supplying a reset potential to said floating diffusion region in response to a reset signal; and a transfer circuit configured to transfer the signal charges in said accumulating region to said floating diffusion region when being operated, while being configured to stop said transfer when not being operated, wherein said control circuit is configured to control said transfer circuit of each said pixel circuit so as to operate said transfer circuit during a complete transfer period required for said transfer circuit to transfer a maximum signal charge accumulative quantity (Qpdmax) in said accumulating region from said accumulating region to said floating diffusion region, and so as to continue to operate said transfer circuit during a first period after the elapse of said complete transfer period, said maximum signal charge accumulative quantity is determined by capacitance value of said accumulating region, said control circuit further controls said reset switch so as to keep an electrically separated condition between said floating diffusion region and said power supply node while said transfer circuit is operated, and a capacitance value (Cfd) of said floating diffusion region is not less than a sum of a first capacitance value required to receive said maximum signal charge accumulative quantity, and a second capacitance value required to receive said signal charge generated by said light detector element during said first period.