Battery pack and battery module containing same

A battery pack, comprising:

• a plurality of batteries arranged in a first direction, each battery of the plurality of batteries including an electrode terminal thereon;
• a first bus bar electrically connecting at least two adjacent electrode terminals of two of the plurality of batteries;
• a second bus bar electrically connecting another at least two adjacent electrode terminals of two of the plurality of batteries
• a bus bar holder accommodating the first and second bus bars in the first direction, the bus bar holder including an inter-bus bar length adjuster between the first bus bar and the second bus bar,
• wherein the plurality of batteries each with the electrode terminal provide a plurality of electrode terminals in the battery pack,
• wherein the bus bar holder includes a first unit bus bar holder and a second unit bus bar holder, the first and second unit bus bar holders:
• being between the first bus bar and the batteries and between the second bus bar and the batteries, respectively,
• having holes through which the electrode terminals extend to be attached to the first and second bus bars, and
• having a first settling groove and a second settling groove in which the first bus bar and the second bus bar are respectively settled, and
• wherein the bus bar holder including the inter-bus bar length adjuster has an elastic bellows structure.