Abstract: The invention concerns a device for the non-destructive measurement of the remanent flux density of magnetic recording media, by recording a specific signal and reproducing the recorded signal by means of two pairs of magnetic recording and playback heads arranged opposite one another and perpendicular to the plane of the recording medium, the ratio of the distance between the individual magnetic heads of each pair of heads to the wavelength of the recorded signal being within a specific range, and the said distance being such that a magnetic recording medium is movable symmetrically between the pair of heads, a common measuring unit being associated with the playback pair. Further features of the device relate to the design of the magnetic recording and playback heads, the measuring unit and the rate at which the particular magnetic recording medium being tested moves between the pairs of heads.