BATTERY PACK

A battery pack includes a battery set and a battery monitoring unit, is provided. The battery set includes multiple battery units. The battery units are disposed side by side in a column direction. In the column direction, the battery unit located at one end of the battery set has an expansion portion. The expansion portion is formed in a center region of an end surface of the battery set in the column direction. The battery monitoring unit is disposed on the end surface of the battery set. In the column direction, the battery monitoring unit is staggered from the expansion portion.