An antenna structure including a first grounding layer, a microstrip line group, a first conductive layer, a first radiator and a second radiator is provided. The microstrip line group is disposed above the first grounding layer and includes a first microstrip line and a second microstrip line perpendicular to each other. The first microstrip line includes a first feeding end. The second microstrip line includes a second feeding end. The first conductive layer is disposed above the microstrip line group and includes a first slot and a second slot perpendicular to each other. The first slot and the second slot correspond to the first microstrip line and the second microstrip line respectively. The first radiator is disposed above the first slot and the second slot. The second radiator is disposed above the first radiator.