Magnetic susceptibility and proton nuclear magnetic resonance (H-1-NMR) measurements were performed for the quasi-two-dimensional pi-d interacting system lambda-(BEDT-STF)(2)FeCl4 at ambient pressure. Magnetic susceptibility arising from the 3d spins of the FeCl4 anion show an anisotropy at low temperature and its temperature dependence for the external field parallel to the c axis is described as a broad peak structure at 8 K. A sharp peak in the temperature dependence of T-1(-1) associated with the antiferromagnetic (AF) transition is observed at T-AF = 16 K, together with the drastic splitting of the NMR spectrum below T-AF. The relation between the static susceptibility and the splitting of the NMR shift suggests the existence of the relatively strong d-d AF interaction. These results can be explained by the model considering the AF-coupled d-spin system in the AF long-range-ordered pi-spin system. We find that the AF phases in lambda-type salts can be universally explained by this model.