The present invention provides an antenna apparatus which can realize favorable communication properties while achieving downsizing of a casing of an electronic device when incorporated in an electronic device. An antenna module (1a) which is incorporated in a mobile phone (130) and which is enabled to perform communication by receiving a magnetic field transmitted from a reader/writer (120) comprises an antenna coil (11a) which is wound in a clearance (132) between an end portion (133b) of a metallic plate (133a) opposing the reader/writer (120) within a casing (131) of the mobile phone (130) and an inner peripheral wall (131a) of the casing (131) so as not to surround an outer peripheral portion of the metallic plate (133a) and which is inductively coupled with the reader/writer (120).