An antenna module includes a base member made of a resin and a copper-foil material, a first ground layer formed on a first surface of the base member, a second ground layer formed on a second surface of the base member, and an inverted-F metal-plate antenna provided on the first surface, formed by punch-cutting and folding a metal plate and including a rectangular conductive plate, a grounding conductor portion connected to the first ground layer, and a feeding conductor portion connected to a feeding point. The rectangular conductive plate is folded at a folding portion extending in a length direction and is divided in a width direction at the folding portion into a first rectangular conductive plate and a second rectangular conductive plate. The first rectangular conductive plate is parallel to the base member whereas the second rectangular conductive plate is inclined to the base member.