[en] The distributions of approximately 7000 flares of importance >= 1 were plotted relative to the sector-structure boundaries of the interplanetary magnetic field (+-) and (-+) extrapolated to the Sun. The data obtained for the time period July 1955 - December 1961 were used. The distributions obtained were analy ed jointly with the same distributions for 1964-1974. It is shown that stable concentration of the flares is observed only near the boundaries (-+) for both hemispheres of the Sun during the increase of the activity and near the maxima cycles No 19 and 20. There are no difference between ''Hale'' and ''non-Hale'' boundaries for these flares. The decrease of the flares was revealed even near the boundary type (+-). For activity decrease phase, after the Sun's general field polarity inversion the concentration of the flares to the boundaries is absent. The difference between Hale and non-Hale boundaries for flares is revealed only in some increase of the flare concentration near the Hale boundaries. The results obtained are likely to give additional evidence in favour of solar magnetic field and flare activity connection