ELECTRICITY STORAGE DEVICE

The herein disclosed electricity storage device includes the case and an electrode assembly accommodated in the case. The case includes a first wall having a first side and a second side, and includes a second wall being opposed to the first wall. The electrode assembly includes a laminate part in which the positive electrode and the negative electrode are laminated along an opposed direction of the first wall and the second wall. The first wall includes a base part and a hollow part protruding from the base part toward the electrode assembly. The hollow part includes an inclined part from the base part toward the electrode assembly and a bottom part that is positioned closer to the electrode assembly than the base part. The base part includes a recessed part between the hollow part and the first side.