NOVELTY - The battery has a positive electrode external terminal (60) and a negative electrode external terminal (70) including a base part (61) with an upper surface (71a) in which a bus-bar (50) is mounted. A protrusion part (62) is provided with a contact surface (51a) on a side surface from the base part. The contact surface is in contact with the protrusion part with respect to the base part, and inclines with respect to a wide surface. The contact surface of the bus-bar is parallel to a contact surface (52a) of the protrusion part, and is joined by a boundary part of the contact surfaces.    USE - Assembled battery e.g. square secondary battery (claimed) such as lithium ion battery, for a vehicle. Can also be used as a nickel-hydrogen battery, a nickel cadmium battery and a lead acid battery.    ADVANTAGE - The contact surfaces can be matched on an inclined surface of the positive electrode external terminal and the negative electrode external terminal such that variation in a design position generated between the positive electrode external terminal and the negative electrode external terminal can be absorbable, so that welding with the contact surfaces of the bus-bar and inclined surfaces of the positive electrode external terminal and the negative electrode external terminal can be performed favorably, thus ensuring sufficient welding strength. The protrusion part of the positive electrode external terminal and the protrusion part of the negative electrode external terminal are made line symmetrical with respect to a straight line, which ties the center of the protrusion part of the positive electrode external terminal and the center of the protrusion part of the negative electrode external terminal, so that space of the protrusion part of the positive electrode external terminal and the protrusion part of the negative electrode external terminal can be shared, thus improving workability of the battery and reducing cost of the battery.    DESCRIPTION OF DRAWING(S) - The drawing shows an exploded perspective view of an external terminal of a square secondary battery with a bus-bar.    Bus-bar (50)    Contact surfaces (51a, 52a)    Positive electrode external terminal (60)    Base part (61)    Protrusion part (62)    Negative electrode external terminal (70)    Upper surface (71a)