A coupled inductor structure applied in a first dielectric layer and a second dielectric layer disposed under the first dielectric layer includes a first inductor element disposed on the first dielectric layer and a second inductor element disposed on the second dielectric layer. The first inductor element has a first bending segment, a second bending segment connected to the first bending segment, and a third bending segment connected to the second bending segment. The second bending segment of the first inductor element has on the second dielectric layer a projection intersecting a second bending segment of the second inductor element. A relative position of the first bending segment of the first inductor element to a first bending segment of the second inductor element is opposite to another relative position of the third bending segment of the first inductor element to a third bending segment of the second inductor element.