Structure of Magnetic Fields of Primary Components of Close Binary Systems BD$$-$$19 5044L, HD 37017, HD 98088

The magnetic field structures of the primary components in three close binary systems have been studied. In all their properties, they do not differ from single magnetic stars. There are signs that the rotational momentum is lost in two ways: 1) it is transferred to the clouds surrounding the magnetic protostar along the field lines and 2) through tidal interactions with a close component. Within the hypothesis of the fossil origin of magnetic stars, a possible scheme for the formation of close binary systems with a magnetic companion has been considered.