In an antenna apparatus, a power feed antenna includes a coil conductor and connected to a power feed circuit, a first booster conductor coupled to the coil conductor of the power feed antenna through an electromagnetic field, the first booster conductor having a planar plate shape, and a second booster conductor coupled to the first booster conductor through an electromagnetic field and coupled to the power feed antenna through an electromagnetic field. Thus, the antenna apparatus is much less influenced by nearby metallic objects and a shape of an included radiation plate may be more freely determined without requiring a highly accurate positional relationship between the radiation plate and the coil conductor.