A thermal processing method selects a batch size range including the number of workpieces to be processed from a plurality of batch size ranges including batch size ranges in which reference numbers smaller than the holding capacity of a workpiece holder are maximums. The workpieces are distributed in the workpiece holder on the basis of the workpiece distribution pattern determined corresponding to the specified batch size range. Processing conditions of the thermal process are determined according to the workpiece distribution pattern. A thermal processing apparatus comprises a controller capable of carrying out the thermal processing method.