Black phosphorus (BP), a material consisting of monoatomic phosphorene layers stacked via van der Waals bonding, is a narrow-gap semiconductor in ambient pressure. It has recently been predicted that BP undergoes a topological transition by applying high pressure, resulting in a semi-metallic band structure. α-EuP₃ has a crystal structure closely related to BP and contains magnetic Eu²⁺ ions between the P layers. Recent first principle calculations predict that semi-metallic band structures originating mainly from the p-orbital of phosphorus are realized in α-SrP₃, which is an isostructural crystal of α-EuP₃. Therefore, in α-EuP₃ we expect the emergence of non-trivial electronic transport derived from the correlation between magnetism and the semi-metallic electronic structure. So far, we have observed the anomalous Hall effect, which abruptly emerges at a certain value of magnetization. This suggests that the magnetically tuned band structure plays an important role. In this presentation, we will discuss the correlation between the exchange splitting and the electronic transport properties, and also the possibility of a topological origin of the anomaly.