A magnetic annealing apparatus is provided which performs a magnetic annealing on workpieces held in a workpiece boat by using a horizontal superconducting magnet as a magnetic field generating unit. The magnetic annealing apparatus includes a carrier configured to accommodate the workpieces before the magnetic annealing process; and a workpiece conveyance mechanism configured to convey the workpieces held in the carrier to the workpiece boat. The workpiece conveyance mechanism is capable of holding the workpieces in either a horizontal state or in a vertical state.