PURPOSE: To provide a burning furnace in which a color changing can be easily performed and a uniform burning can be carried out.

CONSTITUTION: A burning furnace comprises a furnace core pipe 2 arranged in a lateral direction, a furnace body 4 enclosing a circumference of the furnace core pipe 2, and heaters 7A and 7B arranged within the furnace body 4 so as to heat the furnace core pipe 2. The furnace body 4 comprises a furnace main body 4a storing the furnace core pipe 2 and having its upper surface opened, and a lid member 4b for closing its upper surface. The heaters 7A and 7B are arranged at each of opposing inner side surfaces 8A and 8B of the main body 4a of the furnace body, respectively, and at least one of the heaters 7A (7B) is inclined and arranged at an orientation with the upper surface of the main body of the furnace being spaced apart from the other heater 7B (7A) from the bottom part of the main body of the furnace body.