A hermetically sealed battery is provided with a sealing member for air-tightly sealing the through-hole of a battery case from the outside. The sealing member has: a covering member secured to the battery case from the outside; an insertion portion inserted into the through-hole; an annular pressure contact portion in air-tight pressure contact with the hole surrounding portion of the battery case; and a connecting portion disposed between the insertion portion and the annular pressure contact portion so as to be integral with the insertion portion and the annular pressure contact portion. The connecting portion is provided with an annular groove surrounding the insertion portion.