An antenna connection device is provided, which includes: a flat plate-shaped fixing part; a first tension portion extending from an end of the fixing part and bent around; a free part including a long oblique portion extending from an end of the first tension portion and bent and extended so as to oppose the fixing part, and a short oblique portion bent and extended from an end of the long oblique portion; a second tension portion extending from the other end of the fixing part and bent around; and a supporting part including a flat portion flatly extending from an end of the second tension portion, and a curved surface portion bent and extended from an end of the flat portion so as to oppose the fixing part and bent around and extended toward the first tension portion, the curved surface portion being disposed under the free part.