A battery pack comprising: a plurality of battery modules that includes a plurality of battery assemblies and a bus bar for battery assemblies, the plurality of battery assemblies including a plurality of battery cells connected to each other in parallel, being provided to be erected in a height direction in which a positive electrode and a negative electrode are opposite to each other, and being arranged in an even number in a first direction orthogonal to the height direction, the bus bar for battery assemblies connecting the battery assemblies adjacent to each other in the first direction in series; and a bus bar for modules that is provided on one side of the plurality of battery modules in the height direction, and connects the battery modules that are adjacent to each other among the plurality of battery modules, in series, wherein the bus bar for modules includes a first bus bar for modules that is provided in a battery module on one side between the battery modules adjacent to each other, a second bus bar for modules that is provided in a battery module on the other side and is different from the first bus bar for modules, and a connection portion that connects the first bus bar for modules and the second bus bar for modules, wherein the first bus bar for modules includes a first connection counter surface, the second bus bar for modules includes a second connection counter surface, and the connection portion connects the first bus bar for modules and the second bus bar for modules to each other in a state in which the first connection counter surface and the second connection counter surface face each other. a plurality of battery modules that includes a plurality of battery assemblies and a bus bar for battery assemblies, the plurality of battery assemblies including a plurality of battery cells connected to each other in parallel, being provided to be erected in a height direction in which a positive electrode and a negative electrode are opposite to each other, and being arranged in an even number in a first direction orthogonal to the height direction, the bus bar for battery assemblies connecting the battery assemblies adjacent to each other in the first direction in series; and a bus bar for modules that is provided on one side of the plurality of battery modules in the height direction, and connects the battery modules that are adjacent to each other among the plurality of battery modules, in series, wherein the bus bar for modules includes a first bus bar for modules that is provided in a battery module on one side between the battery modules adjacent to each other, a second bus bar for modules that is provided in a battery module on the other side and is different from the first bus bar for modules, and a connection portion that connects the first bus bar for modules and the second bus bar for modules, wherein the first bus bar for modules includes a first connection counter surface, the second bus bar for modules includes a second connection counter surface, and the connection portion connects the first bus bar for modules and the second bus bar for modules to each other in a state in which the first connection counter surface and the second connection counter surface face each other.