The present invention provides an electrochemical device which can guarantee the production rate while improving the long-term reliability. The electrochemical device includes a container 10, an electricity storage element 20, and a structure body 50. The container 10 includes a container main body 11, a lid 12 connected with the container main body 11, and an electrolyte 30 packaged inside the container 10. The electricity storage element 20 comprises a first electrode layer 21, a second electrode layer 22 and a separating member 23 for accommodating the electrolyte between the first and second electrode layers. The structure body 50 is arranged on one of the inner surfaces of the container main body 11 and the lid 12. By compressing and deforming the electricity storage element, a thin wall portion 23a of which the thickness is less than that of the peripheral parts in a region is arranged in the region of the separating member 23 clamped between the first and second electrode layers 21, 22.