Abstract: The present invention discloses a reserve battery having an all solid state thin film battery (5). The reserve battery includes: a housing (1) made of a conductive material; an insulation coating (2) formed on the inner surface of the housing (1); an all solid state thin film battery formed in the housing; a switching System (3) disposed between the housing (1) and the all solid state thin film battery; and an external (6) terminal electrically connected to the all solid state thin film battery, for externally providing electrical connection through the opened surface of the housing. The reserve battery overcomes disadvantages of a general reserve battery using an electrolyte solution.