To provide a power storage device including a gas exhaust part for surely exhausting gas in the desired time after gas generation to the outside in simple structure.

In the power storage device in which an electrode part is incorporated in a housing part 13 made of a laminate film 21, terminals 10, 11 of a positive electrode and a negative electrode connected to current collectors are extended outward, and then the periphery of the housing part 13 is sealed with a sealing part 22 formed over the whole periphery, a buffer part 23 formed by laminating the laminate film 21 is formed between the housing part 13 and the sealing part 22 other than the extended part, a gas exhaust part 25 sealed in a ring shape and including a second sealing part 24 formed by sticking laminated laminate films 21 so as to have peel strength weaker than that of the sealing part 22 in at least one part is formed in the buffer part 23, and a gas exhaust hole 26 is pierced in the laminate film 21 inside the gas exhaust part 25.