[PROBLEM] In space-conservative fashion, at low cost, and with high efficiency, to carry out absorption of gas produced at the interior of a battery. [SOLUTION MEANS] Secondary battery 21 is provided with case 3 in which positive electrode 10 and negative electrode 11 are sealed together with electrolyte, and with explosion prevention valve 4 for allowing escape of high-pressure gas present at the interior of case 3 when pressure within case 3 rises; and is further provided with gas absorber 13 or 14 for absorbing high-pressure gas. Gas absorber 13, includes gas-absorbent material 6 and capsule 5, which comprises hot-melt material, and is provided within case 3, this capsule 5 including, at the interior thereof, gas-absorbent material 6. Furthermore, gas absorber 14, which may be provided outside case 3, may include gas-absorbent material 6; cartridge case 14a which houses, at the interior thereof, gas-absorbent material 6; gas inlet valve 14b for causing high-pressure gas to flow thereinto; and gas outlet valve 14c for causing high-pressure gas to flow out therefrom.