To cook rice porridge of desired thickness by providing a boiling timer for setting a prescribed boiling keeping time and variably controlling a heating quantity between a boiling temperature and a prescribed boiling temperature lower than the boiling temperature by a prescribed temperature.

In a rice porridge cooling control, a rice cooling heater is energized and controlled and the temperature of the inner pot is raised to a water absorption temperature T1°C so as to absorb the water for a set water absorption time t1. Successively, the rice cooling heater is energized and controlled at a full power state and when the temperature of the inner pot exceeds the boiling temperature T3°C, a boiling timer having a fixed set boiling keeping time t2 is started irrelevant to the quantities of the rice and water in the pot. In the set boiling keeping time t2 interval, the output of the boiling heater is increased/decreased between the boiling temperature T3°C and a power-up temperature T2°C a little bit lower than the boiling temperature T3°C so that the total inner pot heating quantity is variably controlled. This constitution can perform appropriate rice porridge cooling according to the rice and water quantities in the inner pot without judging the quantity.