Disclosed is a magnetic annealing apparatus including a processing container having a horizontally-elongated tubular shape and configured to perform a magnetic annealing processing on a plurality of substrates accommodated therein in a magnetic field; a heating unit provided to cover at least a part of a surface of the processing container that extends in a longitudinal direction, from outside; a magnet provided to cover the heating unit from the outside of the heating unit; a substrate holder configured to hold the plurality of substrates within the processing container; and a heat shielding plate provided to surround a part of the substrate holder.