An antenna structure including a metal outer cover and an antenna assembly is provided. The metal outer cover has a bent slit. The antenna assembly is stacked on the metal outer cover and covers a portion of the bent slit. The antenna assembly includes a substrate and an antenna pattern disposed on the substrate. The antenna pattern includes a feed end, a first ground end and a second ground end. In the antenna pattern, a first loop and a second loop are formed from the feed end to the first ground end in two respective paths. A third loop is formed from the feed end to the second ground end. The first loop and the third loop resonate with the bent slit to generate a low frequency band and a portion of a high frequency band. The second loop and the third loop resonate with the bent slit to generate another portion of the high frequency band. An electronic device having the antenna structure is further provided.