© 2020 ISIJ. The effect of magnetic fields on solid-liquid reactions in the Fe-Ga binary system was investigated using Fe/Ga diffusion couples. The reaction and phase growth proceeded by diffusion-controlled process for both 0 and 10 T. It is found that the growth of the intermetallic phases was suppressed by magnetic fields of 10 T regardless of whether α-Fe was in a ferromagnetic or paramagnetic state. The pre-exponential factors in the parabolic coefficient of the Fe3Ga + eutectic region at 0 and 10 T were 2.50 ×104 m2/s and 1.32 ×103 m2/s, respectively. Meanwhile, activation energies at 0 and 10 T were 336 kJ/mol and 318 kJ/mol, respectively, which indicated the ineffectiveness of magnetic fields. That is, reduction of pre-exponential factor of the parabolic coefficient leads the magnetic-field-induced suppression of the reaction in Fe/Ga.