The per­for­mance of the mag­netic sys­tem of a 12 MeV elec­tron race-track mi­cro­tron (RTM) which is under con­struc­tion at the Uni­ver­si­tat Politècnica de Catalunya (UPC) is de­scribed. The RTM mag­netic sys­tem con­sists of two four-pole end mag­nets with the main field level about 0.8 T, one quadru­pole and four beam ex­trac­tion dipoles. As a source of the mag­netic field in these mag­nets a Sa-Co rare earth per­ma­nent mag­net ma­te­r­ial is used. This helps to get a quite com­pact de­sign of the RTM and al­lows to place the mag­netic sys­tems in a high vac­uum en­vi­ron­ment of the ac­cel­er­a­tor vac­uum cham­ber. We dis­cuss re­sults of nu­mer­i­cal sim­u­la­tions of the tun­ing of the end mag­nets by mean of spe­cial tuners and de­scribe their en­gi­neer­ing de­sign which per­mits to as­sem­ble the mag­nets and fix the Sa-Co blocks with­out glu­ing. Also a method and re­sults of mag­netic field dis­tri­b­u­tion mea­sure­ments and mag­net tun­ing are re­ported.