The purpose of the present invention is to provide an antenna device that makes it possible to ensure satisfactory communication performance even when the antenna device is mounted in an electronic apparatus with limited mounting space. An antenna device, incorporated in an electronic apparatus, which communicates with an external device via an electromagnetic field signal, comprising: a metal plate provided inside a housing of the electronic apparatus and facing the external device, and an antenna coil provided by winding a conducting wire in a approximately rectangular shape so that parts of the conducting wire that face each other in a width direction via an opening of the antenna coil come close to each other, and inductively coupled to the external device, wherein the antenna coil is provided along a side face of the metal plate.