A dual band antenna is provided. The dual band antenna includes a grounding portion, a connecting portion, a feeding portion, a radiating portion, a first radiating portion and a second radiating portion. The connecting portion is vertically connected to the grounding portion. The feeding portion has a first end and a second end, wherein the first end is connected to the connecting portion and the second end has a feeding end. The radiating portion is parallel to the grounding portion and vertically connected to the connecting portion. The first radiating portion has a third end and a fourth end, wherein the third end is connected to the radiating portion and the fourth end extends toward the radiating portion. The second radiating portion is vertically connected to the radiating portion.