An antenna array for a high frequency device includes a plurality of antenna elements used for a radar device and arranged in a two-dimensional array in a predetermined area. The plurality of antenna elements includes grouped on-elements and single on-elements with specific distance for grating lobe cancellation, each of them is electrically connected to a phase shifter. The on-elements are arranged such that density of the on-elements at a center portion in the two-dimensional array is high and density of the on-elements at four corners in the two-dimensional array is low.