The purpose of this study was to examine the cause of fluctuations in combustion. It is important to understand the changes that occur in flame kernel development and in flame propagation during cyclic variation.In this study, a comparison was made between time-series variations in OH emission with THC concentration, and the intensity of the combustion reaction and the direction of flame propagation are also discussed. Early flame development and cyclic variation at an early stage of combustion were demonstrated by simultaneously measuring a two-dimensional image of flame emission and the time-series variation of local flame emission. The instantaneous intensity at Cassegrain measurement point agreed with the intensity of time-series variation in local flame propagation at CCD recorded timing. Variations in THC concentration in the cylinder were compared with time-series variations in local flame emission. It was confirmed that the THC decrease and the start of the OH radical emission occurred at almost the same time.