An electrostatic discharge protection device includes a first well region, a second well region, a first doped region, and a first heavily doped region. The first well region and the second well region are disposed in a semiconductor substrate. The first doped region is disposed in the first well region and the second well region. The first heavily doped region is disposed in the first doped region in the first well region. The first well region and the first doped region have a first conductivity type, and the second well region and the first heavily doped region have a second conductivity type that is the opposite of the first conductivity type.