To provide a plane antenna device for improving the compatibility the plane antenna device with an electric circuit and improving productivity by facilitating lamination.

A radiation element 4 is composed of a conductor board provided on the front face of a first dielectric board 2, a ground conductor board 1 is composed of a conductor board provided on the rear face of this first dielectric board, a second dielectric board 5 is provided in front of the first dielectric board 2, an unwanted radiation suppressing conductor board 11 is composed of a conductor board provided on the front face of this second dielectric board 5, and these first and second dielectric boards 2 and 5 are piled.