An antenna module is to be installed in a communication device. The antenna module includes a dielectric substrate that has a multilayer structure, a ground electrode that is disposed in the dielectric substrate, and a first radiating element that has a flat plate shape. The first radiating element has a first surface (a smooth surface) and a second surface (a rough surface) that has a higher degree of surface roughness than that of the smooth surface. The smooth surface of the first radiating element faces the ground electrode.