Provided is an antenna device including a feeding antenna conductor, a non-feeding antenna conductor, a ground conductor, and an artificial magnetic conductor disposed between the feeding antenna conductor and the non-feeding antenna conductor, and the ground conductor. The antenna device further includes a conductor that electrically connects the artificial magnetic conductor to the ground conductor. The conductor is disposed at a position opposite to the feeding antenna conductor with respect to the non-feeding antenna conductor, and is separated from the non-feeding antenna conductor.