PURPOSE: To avoid the simultaneous ignition and combustion at a certain time due to the storage of a large quantity of unburnt kerosine in a combustion chamber by repeatedly pressing an operation switch owing to ignition miss in a petroleum water heater for burning fuel by automatically injecting the fuel by a fuel injection unit based on the operation of the switch provided in an operation unit and igniting it by an igniter.

CONSTITUTION: Fuel is automatically injected from an injection nozzle 40 by the operation of an operation switch 62, injected fuel is ignited by an igniter 54, and the presence or absence of a flame is detected by a flame detecting sensor 56. In this case, when the fuel injection from the nozzle 40 is repeated while there remains no detection of the flame by the sensor 56, the number of times is stored in counter means, and when the number of the counts reaches a set number, the operation of a petroleum water heater 10 is disabled.