Power storage device

A power storage device, comprising:

• a plurality of power storage cells aligned along a first direction;
• and
• an insulator member having a shape extending from a power storage cell disposed at one end of the plurality of power storage cells in the first direction to a power storage cell disposed at the other end of the plurality of power storage cells in the first direction, wherein
• the plurality of power storage cells each have a valve locating surface, and each valve locating surface includes a safety valve,
• the insulator member is in contact with the valve locating surface and includes a plurality of intermediate vulnerable portions, and
• each intermediate vulnerable portion is formed at a position opposed to between a pair of power storage cells adjacent to each other in the first direction, and extends in a second direction orthogonal to both the first direction and an up-down direction of the power storage device.