To produce a planar antenna without depending on the etching technology.

A 1st recessed part 1e with a cross sectional shape of a patch shaped antenna element is formed on the upper face of a formed body made of a dielectric material, and a 2nd recessed part 1h with a ground plane shape is formed on the lower face. A throghhole 1d penetrating through the formed body 1 is provided at a prescribed position. Then a conductive layer is formed on the entire surface of the formed body 1 and the formed body 1 is subjected to cutting so as to leave only a conductive layer formed on the bottom side of the 1st recessed part 1e and the 2nd recessed part 1h. Thus, the planar antenna is produced.