To heat food more evenly by providing a reflecting means along each wall so that while microwave radiation is passed and made to strike on a food-receptacle part, the microwave radiation incident upon the reflecting means is reflected to the food-receptacle part.

Generally this container 10 is a box shaped in a rectangular parallelepiped, having a bottom wall 12, a front wall 14, a back wall 16, side walls 18, 20, and a top wall. These walls define a space 24 for holding food to be heated, such as popcorn. In this instance a layer of a microwave radiation- reflecting material 25 is provided, which covers the bottom wall 12, and the lower parts of the front wall 14, back wall 16, side wall 18, and side wall 20 respectively. The material 25 forms an array of microwave reflector by which the direction of microwave energy is converted and converged relatively evenly toward the inside of the food. As a result, it becomes unnecessary for a relatively odd-shaped food item to be packed in contact with the packaging in order to be cooked more evenly.