An antenna structure includes a housing and a feeding source. The housing forms a radiating portion, a first coupling portion, and a second coupling portion. The first coupling portion and the second coupling portion are grounded. The feeding source is electrically connected to the radiating portion for feeding current to the radiating portion and divides the radiating portion into a first radiating section and a second radiating section. When the feeding source supplies current, the current flows through the first radiating section and is coupled to the first coupling portion to activate a first operation mode and a second operation mode. When the feeding source supplies current, the current flows through the second radiating section and is coupled to the second coupling portion to activate a third operation mode and a fourth operation mode.