To provide a method for operating a microwave heating furnace which does not deform nor crack a workpiece in heating and calcining the workpiece by using microwaves, and a placing table for the workpiece.

The operating method for the microwave furnace comprises calcining the workpiece consisting of a ceramic material by the microwave heating furnace. The placing table having a microwave absorptivity nearly equal to that of the workpiece is selected and used as the placing table which is used in the microwave heating furnace and on which the workpiece is placed. The placing table for the workpiece is the table on which the workpiece consisting of the ceramic material is placed in the microwave heating furnace and has the microwave absorptivity nearly equal to that of the workpiece. The workpiece is preferably a ceramic honeycomb. The placing table is preferably formed by mixing ≥2 kinds of dielectric substances having different microwave absorptivities and the dielectric substances are preferably alumina powder and silicon carbide powder.