A semiconductor substrate thermal treatment apparatus enables excellent heating control in suppressing influence of mutual induction between induction heating coils even when the induction heating coils are arranged in the vertical direction while providing horizontal magnetic flux to susceptors. The apparatus indirectly heats wafers mounted on horizontally-arranged susceptors including induction heating coils to form alternate-current magnetic flux in a direction parallel to a mount face of the susceptor. The wafer are arranged at an outer circumferential side of the susceptor. The induction heating coils are structured with at least one main heating coil and subordinate heating coils electromagnetically coupled with the main heating coil. Inverse coupling coils inversely-coupled to the subordinate heating coils are provided to the main heating coil, and zone control means separately controls a power ratio while synchronizing frequencies and current waveforms of current to the main heating coil and adjacent subordinate heating coils.