The authors have developed a non-oxidizing heating system. The newly developed device, which is called an N-2 jet heater, uses the principle of a storage type heat exchanger. By means of employing a set of two heaters, each containing a regenerator, it is possible to heat N-2 gas to 1773 K. The high temperature nitrogen gas maintains a high furnace temperature under non-oxidizing condition. This system has been applied to the tundish heater of a real continuous easter. As a result, the rate of occurrence of inclusion-related defects in the quality of start slab has been reduced to one-fifth to one-third of the past level, This paper presents an outline of the device and describes the effect of its use on steel quality.