In a secondary battery (10) suggested herein, when a gas pressure in a battery case (12) is increased to or above a specified level and a current interrupt valve (26) is consequently raised to a connecting terminal (21) side, a thinned section (71) is broken around a portion that is joined to the current interrupt valve 26, the connecting terminal (21) and an electrode body are electrically interrupted from each other. An insulant (27) is disposed in a portion where the thinned section (71) is broken, and is interposed between both edges of the broken thinned section (71) after the thinned section (71) is broken.