Bus bar

A bus bar, comprising:

• a plate-shaped conductor that connects electrodes of two battery cells, wherein
• the conductor has two fixed parts each fixed to the electrode of a different battery cell, and a plurality of slits that extend in a first direction,
• the slits are arranged along a second direction orthogonal to the first direction,
• one of the fixed parts is disposed on one side in the first direction with respect to the slits,
• another fixed part is disposed on another side in the first direction with respect to the slits,
• the slits include one first slit, and a second slit placed further away from a virtual line that connects the two fixed parts than the first slit, and
• length of the second slit along the first direction is greater than length of the first slit along the first direction.