Disclosed is an electrostatic discharge protection device, which includes a first-type semiconductor substrate, a first diode including a first first-type well and a first second-type well, a second diode including a second first-type well and a second second-type well, a first isolation structure and a second isolation structure. An upper surface of the first-type semiconductor substrate includes a first region where the first diode is formed, a second region where the second diode is formed and a third region located between the first region and the second region. The first isolation structure is formed on the third region to isolate the first diode from the second diode. The first first-type well is electrically connected to the second second-type well through a metal wire above the first isolation structure. The second isolation structure is located under the first first-type well to isolate the first first-type well from the first region.