An antenna apparatus includes: a circuit board that has a main surface and a rear surface opposite to each other; an antenna element that is formed of a metal plate and is arranged at a predetermined distance from the main surface of the circuit board; a plurality of legs that extend from the antenna element toward the circuit board; a ground conductor that is formed on the main surface or the rear surface of the circuit board; a feeding pin that supplies power from the circuit board to the antenna element; and a plurality of comb-shaped capacitor patterns that are formed on one of or both the main surface and the rear surface of the circuit board and are electrically connected between the plurality of legs and the ground conductor.
