The invention relates to a magnetic linear or rotary encoder (1) for monitoring the motion of a body, comprising: an exciting unit (8), which reproduces said motion and has at least one pair of primary permanent magnets (16, 17), which are arranged opposite one another and are magnetically connected to one another by means of a ferromagnetic yoke body (9) and form a measurement field space therebetween; a fine-resolution sensor unit (29; 29′), which is used to determine a fine position value, is arranged in a stationary manner and has a plurality of magnetic field sensors (25, 26, 27, 28); and processing electronics, which evaluate the signals of the fine-resolution sensor unit and have a data memory. Said magnetic linear or rotary encoder is characterised in that a ferromagnetic deflecting body (18) is provided, which deflects at least some of the magnetic field lines of the magnetic field produced by the primary permanent magnets in a direction perpendicular to the magnetisation vector of the primary permanent magnets, that the fine-resolution sensor unit is designed and arranged in such a way that the individual magnetic field sensors of the fine-resolution sensor unit are penetrated by the magnetic field lines deflected by the deflecting body by means of a perpendicular component, that at least the yoke body is made of a thermally treated, ferromagnetic material, and that the fine-resolution sensor unit does not contain a ferromagnetic component.