An over-current protection device includes first and second electrodes and a positive temperature coefficient (PTC) multilayered structure disposed between the first and second electrodes. The PTC multilayered structure includes a first polymer layer that is bonded to the first electrode, an intermediate layered unit that is bonded to said first polymer layer and that includes a second polymer layer, a third polymer layer that is bonded to and disposed between the intermediate layered unit and the second electrode. The first, second and third polymer layers respectively have first, second and third volume resistances, the second volume resistance being higher than the first and third volume resistances.