Within outer cover member 111 of laminated film including resin layer 111c, there is installed electricity generating element 112 thereby to constitute battery body 11, peripheral portion 113 of the outer cover member being sealed. Spacer 12 is provided which has fixing portion 121 by which the battery body is fixed to predetermined position, the spacer being arranged between outer peripheral portion of the battery body and outer peripheral portion of another battery body put on the battery body. In range H1 that includes an overlapped portion 14 between the outer peripheral portion and the spacer and is provided at least around the fixing portion of the outer peripheral portion, there is provided elastic resin portion 13 produced through insert molding of elastic resin. This thin battery exhibits satisfied stability in set condition against vibration of motor vehicle. This thin battery exhibits satisfied fixing stability against vehicle vibration.