The article presents the results of aeromagnetic survey carried out at the Synnyr ultrapotassic igneous massif (North-Baikal region of Russia). GEOSCAN-401-Geophysics unmanned aeromagnetic complex was used to measure magnetic field at low altitude above relief surface. A new geologic-structural information was obtained as a result of the aeromagnetic data processing. It allowed to correct drilling program on the prospecting area.