PURPOSE: To obtain a sealed battery containing absolutely no water by providing the battery, which has a positive and a negative electrode at least one of which is made of an organic conductive material, with a positive and a negative auxiliary electrode, and sealing the battery after moisture contained in electrolyte is electrolyted and discharged from a venting hole by feeding current to said auxiliary electrode.

CONSTITUTION: An electrolyte 4, a positive and a negative electrode 3 at least one of which is made of an organic conductive material and auxiliary electrodes 2 are installed in a battery case 5. The electrodes 2 and 3 are connected to lead- out electrodes 1, which airtightly penetrate the case 5. The case 5 is provided with a venting hole 6. With the hole 6 open, potential difference necessary for electrolysis of water is applied across the electrodes 2 until water existing in the electrolyte 4 is completely electrolysed, then hydrogen gas and oxygen gas produced by the electrolysis are discharged from the hole 6. At the point when no bubbles are produced entirely, the hole 6 is closed with a sealing plug 7 to seal the case 5. By the means mentioned above, a battery practically containing no water in its electrolyte and allowing entirely no invasion of moisture from the air, is constituted.