Magnetic survey is a geophysical method for solving geological tasks based on studying of the Earth’s magnetic field. It finds a wide application at geological mapping, structural researches, searches of minerals, studying of the geological environment. The magnetic survey is the most effective method of searches and survey of iron ore fields. Ground field magnetic observation is carried out by means of hand-held magnetometers. There are three types of ground magnetic observation: 1) mapping-searching, 2) exploratory 3) prospecting (or detailed). The purpose of mapping-searching magnetic observation is the solving of problems of reconnaissance mapping, and direct searches of ferriferous ores. The purpose of exploratory magnetic observation is specification of anomalies of mapping-searching observation: identification of tectonic dislocations, assessment of the sizes, forms and position of ore bodies. The purpose of detailed prospecting magnetic observation is clarification of the sizes, forms and position of rock swells with various magnetic properties, survey of ore fields, detailed geological mapping.