To hold a temperature for sterilization of miscellaneous bacteria in a warm air case by switching outside air introducing warm air exhausting to warm air circulating in the case at the time of drying dish.

Dishes to be dried are introduced into a dish dryer in an apparatus 1. After drying of the dishes is completed, it is switched to a miscellaneous- bacteria killing temperature. Thus, exhaust air from a blower 2 is heated by a heater 3, the warm air is circulated into the apparatus, not externally exhausted, but again sucked to the blower 2, and circulated in the apparatus. Colibacillus can be killed at high temperature of about 80°C. Therefore, it is controlled to hold at 80°C or higher in the apparatus for several minutes to kill bacteria in the dryer to provide safe dishes. To control to ensure 80°C effective to sterilize the bacteria at the temperature in the dryer even when a room temperature is 0°C, warm air in the dryer is again circulated to expedite temperature rising in the dryer.