The present disclosure relates to a 5th generation (5G) or pre-5G communication system for supporting a higher data transmission rate after a 4th generation (4G) communication system such as long-term evolution (LTE). The present disclosure relates to an antenna device, and the antenna device may include an antenna board including a plurality of antenna elements and a coupler for extracting part of a signal transmitted to the plurality of the antenna elements, and a calibration board disposed under the antenna board, and including a correction circuit for correcting an error using the part of the signal extracted by the coupler, the coupler may include a first transmission line connected with the plurality of the antenna elements, and a second transmission line disposed to be capacitively connected with the first transmission line, and the second transmission line may include a third transmission line and a fourth transmission line spaced apart from each other to be parallel to the first transmission line based on the first transmission line, and a fifth transmission line disposed to connect with the third transmission line and the fourth transmission line with respective terminal ends, and to surround a via hole penetrating the antenna board in a vertical direction.