To contrive the reduction of an initial cost as well as a running cost while preventing the deterioration of the operating efficiency of a furnace effectively and, at the same time, contrive the improvement of the quality of a final product.

A degreasing and sintering furnace is provided with a pair of furnace bodies 1, provided with degreasing and sintering function, as well as a power supply device 2 and a main exhausting device 3, which are common for both of the furnace bodies 1, to permit the parallel operation of a degreasing and sintering process as well as a cooling process while switching the power supply device 2 and the main exhausting device 3 alternately whereby general heat treatment process can be advanced effectively in respective furnaces without stopping either one of the furnace bodies 1 while a furnace body 1, to which the main exhausting device 3 is not connected, is constituted so as to be capable of being exhausted by an auxiliary exhausting device 4 whereby the shortening of exhausting time and the prevention of moisture adsorption can be contrived while vacuum cooling can be applied on a treated matter, whose degreasing and sintering have been finished, by carrying out preliminary exhaust during a waiting time until the main exhaust device 3 is connected.