To provide a wide band antenna substrate which allows for excellent transmission and reception of radio waves over a wide frequency band.

In the antenna substrate, a first patch conductor 7, a second patch conductor 8, and a third patch conductor 9 are quadrilaterals having short sides 7a, 8a, 9a parallel with the first direction and long sides 7b, 8b, 9b parallel with the second direction, respectively, where the area of the second patch conductor 8 is larger than that of the first patch conductor 7, and the area of the third patch conductor 9 is larger than that of the second patch conductor 8. Preferably, the short side 7a of the first patch conductor 7 has the same length as that of the short side 8a of the second patch conductor 8, the long side 7b of the first patch conductor 7 is shorter than the long side 8b of the second patch conductor 8, the short side 8a of the second patch conductor 8 is shorter than the short side 9a of the third patch conductor 9, and the long side 8b of the second patch conductor 8 is shorter than the long side 9b of the third patch conductor 8.