The normal spectral emissivity at 807 nm and molar heat capacity at constant pressure of Fe-Ni melts were successfully measured by the combination of an electromagnetic levitation technique and a static magnetic field. The static magnetic field suppressed the surface oscillation and translational motion of the levitated sample droplet to reduce the experimental uncertainty in the measurements. For all compositions of the melts, the normal spectral emissivity values and molar heat capacities showed negligible temperature dependence. The excess heat capacity of the melts was evaluated as a function of composition. This analysis showed a positive deviation from the Neumann-Kopp rule over the entire composition range. Moreover, enthalpy of mixing was calculated from the excess heat capacity up to 2200 K.