V 1379 Aql is an eclipsing binary consisting a hot subdwarf (sdB) and a red giant star (K0III/IV). According to the brightness variation outside of eclipses, the giant component is a chromospherically active star. The dark and cool active structures on this component and their evolution cause the variation of the total light of the system. Photometric observations spanning 16 years yield the variations of the photometric period and the mean brightness. There is a correlation between them. We suggest that the photometric period decreases as the latitude of the active region moves toward the equator.