Abstract: An object of the present invention is to provide a combustor having a premixing burner, wherein a conical flame can be formed and the metal temperature at a liner and a burner end face can be reduced. The combustor has at least one premixing burners for premixing fuel with air and jetting the mixed gas into a chamber for combustion. A cylindrical guide attached to an outer circumferential portion of an end face of the burner is provided with air supply holes. An interval D1 defined between the adjacent air supply holes and an interval D2 defined between each air supply hole and the outlet end face of the burner are each made narrower than the quenching distance in the premixed gas jetted from the premixing burner.