SECONDARY BATTERY AND ASSEMBLED BATTERY

A secondary battery disclosed herein includes: an electrode body; a battery case; a terminal extracted from a terminal extracting hole to outside of the battery case; and an external conductive member joined to the terminal. The external conductive member has a through-hole into which a part of the terminal is inserted, and a joining portion between the external conductive member and the terminal is formed at a peripheral edge of the through-hole. The external conductive member has an approximately annular thin portion provided around the joining portion, and the thin portion is configured to melt when a current of 1000 A or more flows through the secondary battery.