The invention provides an antenna device and a mobile phone. The antenna device includes a substrate, a slot provided in the substrate so that the slot includes a cut opening that is close to an edge of the substrate and the slot includes a crooked portion, a conductor section configured to include a slit in an area of the substrate, the area being sandwiched by the slot in the crooked portion, and an antenna that is placed close to the conductor section and is side by side with a surface of the substrate.