To provide a secondary battery which suppresses the deterioration of the battery performance without increasing the number of components.

The secondary battery 100 houses a power generation element in a case 50. A pattern groove 11 is formed on a first surface 51 of a case body 10, and a pattern groove 12 is formed on a second surface 52 which is a back side of the first surface 51. In the secondary battery 100, each pattern groove 11 or 12 presses the power generation element in the case 50, and the case 50 itself presses the power generation element from both sides in the facing direction. Further, in the secondary battery 100, the patter grooves 11 and 12 has the same pattern. The pattern grooves 11 and 12 are misaligned with each other in a surface direction which intersects the direction that the first surface 51 faces the second surface 52.