An antenna including an antenna structure disposed on a substrate is provided. The antenna structure includes a first radiation part, a second radiation part, a metal coupling part, a third radiation part and a feeding point. The first radiation part has a first bend, a second bend and an opening end. The first radiation part extends from a grounding point of a grounding plane and the opening end thereof is nearing the grounding plane. The second radiation part extends from a section between the first bend of the first radiation part and the grounding point. The metal coupling part is nearing the first radiation part and the second radiation part. The third radiation part is disposed between the second radiation part and the grounding plane, and extends from the metal coupling part. The feeding point is coupled to where the third radiation part and the metal coupling part connected.