A sealing structure for an electronic device, and an antenna apparatus, which are able to alleviate load caused on the electronic device when a flexible sheet is bent, are provided. A sealing structure 9 that seals an electronic device 41b mounted on a polygonal sheet 40 that is bendable has: a first resin plate portion 91 and a second resin plate portion 92, which are hard and interpose the electronic device 41b via the polygonal sheet 40 from a top surface and a back surface of the polygonal sheet on which the electronic device 41b is mounted； and an elastic body 93 that is provided on an outer periphery of the first resin plate portion 91 and the second resin plate portion 92 and integrally molded so as to press the first resin plate portion 91 and the second resin plate portion 92 against the polygonal sheet 40.
