The present application discloses antenna device including first and second antenna elements which communicate radio waves; housing which stores processor for processing signals in response to the radio waves; first and second element covers for storing first and second antenna elements, respectively. First element cover includes first rotary cylinder, which is held by housing and rotatable around first rotational axis, and first protruding cylinder, which protrudes from first rotary cylinder, first rotary cylinder protruding from housing along first rotational axis. Second element cover includes second rotary cylinder, which is held by housing and rotatable around second rotational axis, and second protruding cylinder, which protrudes from second rotary cylinder, second rotary cylinder protruding from housing along second rotational axis. First included angle between first and second protruding cylinders storing first and second antenna elements is changed by rotation of at least one of first and second rotary cylinders.