An electrostatic discharge protection device has a substrate, a P-well, a N-well, and an isolation portion. The P-well and N-well formed in the substrate are neighboring to each other. Along a specific direction, the P-well has a first N-type, a first P-type, a second N-type, a second P-type, and a third N-type high doping regions sequentially located thereon, and the N-well has a third P-type, a fourth N-type, a fourth P-type, a fifth N-type, and a fifth P-type high doping regions sequentially located thereon. The first N-type, the third N-type, the first P-type, and the second P-type high doping regions are coupled to a ground end, the third P-type, the fifth P-type, the fourth N-type, and the fifth N-type high doping regions are coupled to a voltage supply end, and the second N-type and the fourth P type high doping regions are coupled to an input/output end.