Abstract: A gas nozzle having a fired surface excellent in particle reduction effect is provided. The gas nozzle 1 is a columnar gas nozzle made of sintered ceramics, provided with at least one through-hole 2 through which gas flows. The entire inner surface 2a of the through-hole 2 and the end face 1A on which outlet 2b of the through-hole 2 is provided are both fired surfaces. The inner surface 2a of the through-hole 2 has a first region A in the vicinity of the outlet 2b and a second region B which is located at a further position than the first region A. The average crystal grain size in the first region A is formed to be smaller than the average crystal grain size in the second region B.