maximum width w and length l of electrodes 2 a and 2 b in consideration of the margins 1 f can be defined the length l 2 of margin 1 f along long sides 11 b and 1 c need be set to at least 0 05 mm at each of both ends of insulating substrate 1 thus in consideration of margins 1 f the length l 1 of each of electrodes 2 a and 2 b along long sides 11 b and 1 c that can be provided on surface 1 a of insulating substrate 1 is l u2212 0 1 mm the width of electrodes 2 a and 2 b and gap 2 c along short sides 1 d and 1 e is w u2212 0 1 mm margins 1 f can be smaller according to the method for providing the metal in esd protector 1001 of embodiment 1 protective resin layer 5 has a large thickness to have a higher physical breaking strength in esd protector 1001 of embodiment 1 surface 1 a of insulating substrate 1 is roughened to have a large anchor effect which increases the junction area between protective resin layer 5 and insulating substrate 1 this structure can.