A solid-state image pickup device includes: comparators; counters; and a control portion for carrying out control in such a way that in a phase of an addition mode, the two comparators and the two counters corresponding to the two pixel columns, respectively, are set as a unit, 1 is added to a second digit of one counter of the two counters when both the comparison results from the two comparators has a first logic, 1 is added to a first digit of the one counter when one of the comparison results from the two comparators has the first logic, and 1 is added to none of the first digit and the second digit of the one counter when both the comparison results from the two comparators has a second logic.