A solid-state image pickup device includes a first optical signal accumulation unit configured to accumulate a first optical signal obtained by performing an optoelectronic conversion in a first period by an optoelectronic conversion unit, a first reference potential accumulation unit configured to accumulate a first reference potential corresponding to the first optical signal, a second optical signal accumulation unit configured to accumulate a second optical signal obtained by performing an optoelectronic conversion in a second period by the optoelectronic conversion unit, the second period being shorter than the first period, and a combining unit configured to perform a CDS process by using at least the first reference potential accumulated in the first reference potential accumulation unit and combine the first optical signal accumulated in the first optical signal accumulation unit and the second optical signal accumulated in the second optical signal accumulation unit.