In this study, the chamber size was designed and manufactured so as to make a resonance with microwaves in sterilizing moisture-contained food by making good use of microwaves. When the green-pea jelly which was made and sterilized for experimental usage with no addition of an antiseptic was left in the room temperature for 1 minute, 2 minutes or 3 minutes respectively, resulted in delaying more greatly the procession of change in quality of food for almost 7 to 15 days than in unsterilized food. As a result of experiment conducted above, it is considered to produce good results of decreasing the resource waste and environmental pollution, by lengthening the period of preservation and circulation of food.