An antenna module includes a dielectric substrate, a grounding element, a transmission element and a radiating element. The dielectric substrate has a first surface and a second surface. The grounding element is disposed on the first surface. The transmission element and the radiating element are disposed on the second surface. The radiating element includes a first sub-radiating element having a first side and a second side. The first sub-radiation element is connected to the transmission element at the first side, and the width of the first sub-radiating element gradually becomes larger from the first side toward the second side.