An antenna oscillator includes a first strip line type resonator and a second resonator functioning as an antenna. The first resonator is fabricated by stacking a first conductor onto a grounding conductor with a first dielectric part including a gain part therebetween. The second resonator is fabricated by stacking a second conductor, emitting electromagnetic waves to the exterior, onto the first resonator with a second dielectric part therebetween so as to function as an antenna with the configuration between the grounding conductor and the second conductor. The first conductor and the second conductor are separated from each other in a stacking direction with the second dielectric part or the second dielectric part and the grounding conductor therebetween. The first resonator and the second resonator are electromagnetically connected together so as to form a resonance circuit that makes the electromagnetic waves resonate.