Heating device

Patent Pending PROBLEM TO BE SOLVED: To provide a heating device which reduces dispersion in the temperature distribution of a heated object. ; SOLUTION: A small combustion heater comprises: a combustion chamber; a fuel gas supply passage formed to supply fuel gas obtained by premixing fuel and a combustion oxidizer, to the combustion chamber and to satisfy that the representative dimension of a portion facing the combustion chamber is a quenching distance or less;