An antenna element 1 is installed at a glass part 5 of a vehicle 4. The antennal element 1 has a ground part 3 and a radiating element 2. A metallic part side ground part 3b of the ground part 3 is overlapped with a metallic part 6 of the vehicle 4, while a glass part side ground part 3a of the ground part 3 and the radiating element 2 are not overlapped with the metallic part 6. The ground part 3 is installed such that a ratio of the area of the glass part side ground part 3a to be overlapped with the glass part 5 to the area of the metallic part side ground part 3b to be overlapped with the metallic part 6 is from 1:5 to 1:10.