To create an efficient direct flame-type firing furnace for ceramic art, which exhibits the maximum effect with the minimum space, and to equally give a chance to functionally utilize the furnace for ceramic art to persons intending to practically fire respective artistic ceramics.

In the firing furnace, the gap between the periphery of a shelf board 5 and an inner wall 3 is narrowed down so that combustion gas is mixed with secondary air sufficiently, and a chamber surrounded by the gap, the shelf board 5, the furnace bottom 2, and the inner wall 3 is constituted as a mixing gas chamber. Thereby, a completely mixed combustion gas is discharged from the periphery of the shelf board 5 as separate flame. Further, in the firing furnace, the velocity of the combustion gas is increased when the gas passes through the gap, and a chimney 4-1 capable of controlling the length of a part extending into the firing chamber is provided at the center section of a cap 4 so that the combustion gas is not easily exhausted to the outside, and the combustion efficiency of the combustion gas is enhanced. Consequently, it is possible to maintain the inside of the combustion chamber uniformly at a high temperature by forming a passage for the combustion gas.