To stabilize an operation of a protection element 1A in adjusting a resistance value of a heating element 6A by forming a trimming 7 in it, as to one giving rise to blowout of a metal body 4 of a low melting point or tripping of a PTC element by electric conduction and heating of a heating element 6A.

In the protection element having a heating element and a low-melting-point metal body or a PTC element on a base plate, in which a blowout of the low-melting-point metal body or a tripping of the PTC element occur by heating of the heating element, a direction of electricity conduction of the heating element is from electrodes placed on two facing and longitudinal sides of the heating element to an electrode placed on the center of one of the two facing and lateral sides of the heating element. In the heating element, the trimming is formed on the two sides of the electrode in a direction from one out of the two facing lateral sides on which the electrode is placed to the other facing side and formed between the two trimmings formed on the two sides of the electrode in a direction from one side to the other side facing the electrode.