To make the inside of an inner pot return to an atmospheric pressure when finishing steaming by optimally selecting or setting the steaming time after pressure cooking such as stewing except for rice cooking.

After the pressure cooking such as the stewing except for the rice cooking is executed with the inside of the inner pot 3 retained at a prescribed pressure by a pressure valve 33 while heating the inner pot 3 inside a vessel 2 with the lid closed, steaming is executed for a set time for decompressing the inner pot with temperature decrease, and when finishing the steaming, the pressure valve 33 is automatically opened to open the inside of the inner pot 3, or the opening and a notification is executed to attain the purpose.