An antenna member is configured to be mounted on a circuit board and to be used as an antenna. The antenna member has a split ring resonating portion, an impedance matching portion and a feed portion. The split ring resonating portion is provided with a facing portion which forms a split. The split ring resonating portion has a first side portion, a second side portion and an upper portion. The upper portion connects the first side portion and the second side portion with each other. The feed portion is provided on at least one of the first side portion and the second side portion. The impedance matching portion is positioned above the feed portion in an up-down direction perpendicular to a lateral direction. The impedance matching portion couples the first side portion and the second side portion with each other.