To prevent the occurrence of an accident that multiple cylindrical batteries are mounted for use in series erroneously with their positive and negative electrodes arranged reversely to cause a charging state.

A power generating element is filled in a metal container concurrently serving as an electrode terminal, and a metal sealing plate 1 serving as the other electrode terminal is caulked and fixed at a metal container opening section via a resin packing to form this cylindrical battery. A ring-like insulating resin 2 having a lug-shaped section 2 a is fitted to the flange section and side face section of the metal sealing plate 1, and the lug-shaped section 2a covers part of the flat section of the metal sealing plate 1. Even if the metal sealing plates 1 are connected together by the erroneous connection of the batteries, the contact between the metal sealing plates 1 is prevented by lugs, and no charging state occurs.