Partition member and assembled battery

A partition member that forms a partition between single batteries that constitute an assembled battery or between a single battery and a member other than the single battery, wherein the partition member includes

• an encapsulated body capable of retaining a liquid and
• an outer package body having an internal space for accommodating the liquid and the encapsulated body in a sealed state, and
• the ratio of a water absorption rate 2 to a water absorption rate 1, [water absorption rate 2]/[water absorption rate 1], is at least 0.4, where the water absorption rate 1 indicates the water absorption rate when the encapsulated body is compressed for 1 minute at a pressure of 0.05 kgf/cm2, and the water absorption rate 2 indicates the water absorption rate when the encapsulated body is compressed for 1 minute at a pressure of 5 kgf/cm2.