The invention is intended to suppress oscillatory combustion of a combustion apparatus. In the invention, acoustic closed ends are provided at an inlet side and an outlet side of the burner port unit, and the combustion apparatus is constituted so that the flame may be positioned between these closed ends, and a buffer chamber is provided at the inlet side. Thus, when the inlet side and outlet side of the burner port unit of the combustion apparatus are formed as acoustic closed ends, oscillatory combustion occurs easily. At this time, when the intake tube communicates at the upstream side of the inlet side closed end, and an exhaust tube communicates at the downstream side of the outlet side closed end, if the length of the intake tube and exhaust tube is changed, the air ratio and combustion amount for generating oscillatory combustion remain constant, and the oscillation frequency and oscillation pressure remain constant. In such condition, when a sound absorbing unit is provided in the buffer chamber, oscillation does not occur, and if the intake tube or exhaust tube is extended, oscillation does not occur.