NOVELTY - A polymer gel electrolyte comprises polymer electrolyte composition (A) containing electrolysis salt which is sulfonylimide lithium salt, non-aqueous solvent (B), 2-40 wt.% polyvinyl acetal (C) with respect to whole electrolyte, and greater than or equal to 0.3 mass% crosslinking agent (D) with respect to component (C) in which polymer gel electrolyte is gelatinized by crosslinking. Components (A) and (B) do not separate from polymer matrix but keep a gel shape when polymer gel electrolyte is heated to 0-80 degrees C.    USE - A polymer gel electrolyte for primary battery and secondary battery e.g. lithium ion secondary battery.    ADVANTAGE - The polymer gel electrolyte has high safety, excellent shape stability due to high shape freedom degree, and excellent impact resistance and flexibility and can be manufactured easily at a low cost. The three- dimensional matrix structure of polyvinyl acetal which controls and crosslinks sol-gel reaction has excellent liquid holding property of electrolyte solution and high ion conductivity and is excellent in adhesiveness of polymer electrolyte and electrode.    DETAILED DESCRIPTION - A polymer gel electrolyte comprises polymer electrolyte composition (A) containing electrolysis salt which is sulfonylimide lithium salt of formulae LiN(SO2ClF2l+1)2 (1), LiN(SO2ClF2l+1)(SO2CmF2m+1) (2), or LiN(SO2CnF2n)2CF2 (3), non-aqueous solvent (B), 2-40 wt.% polyvinyl acetal (C) with respect to whole electrolyte, and greater than or equal to 0.3 mass% crosslinking agent (D) with respect to component (C) in which polymer gel electrolyte is gelatinized by crosslinking. Components (A) and (B) do not separate from polymer matrix but keep a gel shape when polymer gel electrolyte is heated to 0-80 degrees C.    l-n=0-5.    An INDEPENDENT CLAIM is included for manufacture of polymer gel electrolyte which involves dissolving components (A) and (C) in component (B) to obtain solution, advancing reaction by adding component (D) to obtain sol-form liquid, and further advancing reaction of sol-form liquid and gelatinizing.