A liquid action substance battery having its external terminal welded after assembling the battery in which safety of the battery is enhanced by protecting an explosion-proof valve against being torn apart in the subsequent welding work of the external terminal even if the position of a negative pole action substance being press-bonded to the inner surface of the battery can is shifted and that substance is extruded to the bottom face of the battery can. The liquid action substance battery employing an alkaline metal such as lithium, sodium or potassium or its alloy as the negative pole action substance, and an oxyhalide such as thionyl chloride, sulfuryl chloride or phosphoryl chloride in a liquid state at normal temperature as the positive pole action substance, and storing and sealig the negative pole action substance and the positive pole action substance in the bottomed battery, wherein a metal plate is welded to the inner surface at the bottom part of the battery can to form a partial space between them so that welding heat is not transmitted directly to the negative pole action substance when the external terminal is welded.