A waste incinerator, comprising a combustion chamber for combusting waste, a plurality of sonic gas temperature measuring instruments, a means for estimating a temperature distribution in the combustion chamber, a means for recognizing block addresses, a means for estimating a temperature distribution in each block address, a comparison means for comparing the temperature distributions, a control means for controlling a gas temperature, and a waste heat boiler, wherein a gas temperature distribution in the waste heat boiler is measured by the temperature measuring instrument, and combined with the block addresses in the waste heat boiler.