Abstract: A heat-treating apparatus comprises a heat-treating portion which performs a required heat treating to a plural number of objects to be treated mounted on a heat-treating boat, a vacuum exhaust system which creates a vacuum inside the heat-treating portion, a load lock chamber which is connected so as to be freely openable and closable with respect to the heat-treating portion, which is filled therein with an inert gas and which is for transporting an object to be treated into and out of the heat-treating portion, and a residual treating gas exhaust system which is connected to the load lock chamber.