It has been shown that the complicating factors in fabrication of magnesium diboride samples, such as high sensitivity of Mg to oxidation and the high Mg vapor pressure, can be overcome to realize superconducting thin films and the best results have been achieved by the so-called all-in-situ method. Films produced by this method could be used for fundamental studies of the superconducting properties of MgB2 and they were also suitable for the devices fabrication due to their smoothness and good superconducting properties. In this respect, a magnetometer with directly coupled pick-up loop has been fabricated based on those films. The device incorporated two nanobridges as weak links in the superconducting pick-up loop. The calculated effective area at 0 K of the magnetometer was 0.27 mm2 and its sensitivity to the external flux was 7.4 nT. The effective flux noise was 1.3 pT/Hz1/2 at 14 K, which is sensitive enough for recording adult MCG. This is a satisfactory result and illustrates that magnesium diboride is a very promising material for electronic applications.