After the well-known compound Cd3As2 had been established to be a symmetry-protected 3D Dirac semimetal, this topological semimetal attracted a considerable interest. Magnetic impurities give rise to unusual change of properties of 3D Dirac materials therefore the effect of doping of 3d and 4f impurities on the electrical and magnetic properties of these materials is of importance. We measured the electron spin resonance (ESR), magnetoresistance (MR), and magnetic susceptibility (MS) of Cd3As2 doped by Eu in weak magnetic fields.  Samples of Cd3As2:Eu were prepared from melt. The powder X-ray diffraction confirmed the identity of the compound as being Cd3As2 in the low temperature (α) modification.  For the pure Cd3As2, a weak ESR signal with a g factor ~ 2.15 appears on the background of a strong field derivation of MR at the temperature 100 - 200 K. For europium doped samples at temperature above 300 K, we observed two symmetric ESR signals, with g1 = 2.28 and g2 = 3.9. This allows us to conclude that the small phase consists of Eu2+ ions located in interstices positions - tetrahedral vacancies in a fluorite type cell, whereas the main phase consists of the Eu2+ ions in the positions substituting of the Cd2+ ions. The ESR data show anomalous large values of the g factor of the conduction electrons (gce ~ 16). At decreasing the temperature, conditions of ESR observation become much worse due to strong broadening and disappearance of resonant signals. Usually such behavior testifies to ordering of magnetic impurities.  The magnetic properties were measured in the temperature range 2-400 K using a commercial SQUID magnetometer, with magnetic fields up to 5 T. At high temperatures, the magnetic susceptibility is negative, with the transition to positive values at temperatures below 100 K. At temperatures below 30 K, a transition to a presumably ferromagnetic ordered state begins.  Electrical properties were characterized by a standard four probe method in the temperature interval 12-300 K and at the magnetic field 0.5 T. The measurements resistivity and Hall provide an electron density of ne = 2.2 × 1019 cm−3 (roughly independent of temperature), a metallic resistivity, and a mobility of μ = 6 × 103 cm2/Vs at 12 K. The ratio of resistivity ρ 300K/ ρ12K =18.  The temperature dependence of the resistance of a 3D topological semimetal Cd3As2 doped with a small amount of europium is completely described by an exponential (semiconducting) term with a gap of about 30 K and a linear phonon term with a negative residual resistance, which indicates an unusual scattering of current carriers. However, against such background, we found a weak contribution of current carriers to the resistance, which oscillates with temperature and magnetic field. An analogous contribution is also manifested in the field dependence of the magnetization. Similar phenomena had been earlier observed in magnetic semiconductors [1] and were associated with the temperature dependence of the Fermi level and a change in its position relative to the Landau levels arising in the quantization of electron orbits in a magnetic field. In our case, the appearance of such phenomena can be a consequence of the splitting of the Dirac nodes in the electronic spectrum into the Weyl nodes under the influence of magnetic impurities, as well as of the presence of a hidden semiconductor gap, which affects the population of levels and the behavior of europium ions due to their non-integral valence. Our experimental results were discussed elsewhere in terms of the interaction of magnetic impurities in semimetals with the Dirac fermions [2, 3].