A combustion control device includes a combustion fan motor, a control unit, a silicon diode group, a silicon diode, and a combustion-fan-disconnection detecting unit. The control unit is configured to control a combustion state of the combustion fan motor. The silicon diode group includes at least two silicon diodes coupled in series to the combustion fan motor. The silicon diode is coupled in parallel to the silicon diode group with a reversed polarity. The combustion-fan-disconnection detecting unit includes a photocoupler and a resistor. The photocoupler and the resistor are coupled in parallel to the silicon diode group and the silicon diode with the same polarity as a polarity of the silicon diode group side.