The expression and activity of type 1 NAD(P)H dehydrogenase (NDH‐1) were investigated in Synechocystis PCC 6803 cells during different growth phases (i.e. lag, logarithmic, stationary and decline phases). The relative amount of NDH‐1, estimated by Western blot analysis using antibodies against NdhH, NdhI and NdhK, increased more than two‐fold during growth from the lag to the logarithmic phase and then decreased after the logarithmic phase to reach lowest levels after 15 days (decline phase). The activity of light‐dependent NADPH oxidation and cyclic electron flow around photosystem I (PSI) changed nearly in parallel with the amount of NdhH, NdhI and NdhK in cells across the growth phases. In contrast, the activity of photosynthetic O2 evolution and respiratory O2 uptake was not significantly different across phases of growth; the fluctuation of the activity at different phases was within 40%. These results suggested that the activity of light‐dependent NADPH oxidation and PSI‐cyclic electron flow are restricted by the amount of NDH‐1 and that other factor(s) are limiting the rates of photosynthesis and respiration.