The article presents the results of studies of the magnetic field of chemically peculiar stars in the association of young stars Orion OB1. Our results indicate a sharp drop in the proportion of magnetic stars and a simultaneous decrease in their magnetic field with age. The observations were made with the 6-m BTA telescope of the SAO RAS. On the whole, the obtained data testify in favor of the theory of the relic origin of the magnetic field of chemically peculiar stars. However, the formation process itself may have a number of features that have observational manifestations.