Packaging container for microwave oven

A packaging container for a microwave oven. Completion of heating of the container contents and automatic opening of the container can be easily recognized. This can be achieved without requiring a special member and complex steps, but by processing wrapping materials constructing the packaging container. Also provided is a packaging container for a microwave oven, where danger, including spilling of the contents of the container and burning by touching an opening section occurring in heating by a microwave oven, can be avoided. Further provided is a packaging container for a microwave oven, sealed by heat-sealing plastic films and having a steam vent seal section having a weakened section. The steam vent seal section has mark emerging means, and when the steam vent seal section is separated and opened, the means shows different surface- and back face-wrapping materials constituting the steam vent seal section, enabling recognition of opening.