To provide a power storage element which can prevent a fixing piece in a current collector secured to a case from being broken under exposure to vibration.

A power storage element according to the present invention includes current collectors which are housed in a case together with a power generation element and which are fixed in place by shaft-like members inserted into the case. The current collectors each include a fixing piece disposed along the inner face of the case and a power generation element connection part which is electrically and mechanically connected to the power generation element. The fixing piece includes a base piece connected to the power generation element connection part and a fold-back piece connected to the base piece. The base piece is disposed closer to the case side than the fold-back piece. The fold-back piece is folded back toward the inside of the case and laid on top of the base piece. The shaft-like members fasten the fixing piece while being inserted into the case, the base piece, and the fold-back piece to the case.