To provide anaccident preventing device wherein a customer touches a commodity after the surface of the commodity heated by means of an automatic vending machine is cooled down to a safe temperature by inhibiting the take-out of the commodity until the commodity comes to have a prescribed temperature after it is heated.

Optimum time by the power of a microwave oven is previously set for the commodity. When the value of a heating timer is matched with a value showing the setting time and it is timed up, a lower cover of the microwave oven opens. The product 3 drops via a passage and it is loaded on a reception plate 2 in front of the take-out port 5a of the commodity. The drop of the product is detected by a commodity sensor. When a commodity sensor 4 recognizing that the commodity 3 is loaded on the reception plate 2 detects the commodity, a blower starts cooling and a cooling timer starts an operation. When the cooling timer is matched with setting time and it is timed up, current is made to flow in the electromagnetic solenoid 23 of a lock mechanism 10 at the take-out port 5a of the commodity, and locking is removed. At the same time, the completion of cooking in an operation pat is displayed.