PURPOSE: To provide a separator free from the ingress of an electrolyte, while having the high capability of holding an electrolyte and preventing the appearance of dendrite by impregnating alkali resistant fiber with the bridged state of polyvinyl alcohol having the specified constitutional unit.

CONSTITUTION: Polyvinyl alcohol having a constitutional unit expressed by the general formula is bridged and alkali resistant fiber is impregnated with the polyvinyl alcohol in bridged state. In the formula I, R1 stands for a quaternary aromaticity complex cyclic residual group containing nitrogen, R2 for a hydrogen atom or an alkoxy group and R3 for a hydrogen atom or an acyl group. Also, (m) stands for 0 or 1, and (n) for a natural number between 1 and 6. An alkaline battery separator is formed out of a fabric sheet including that alkali resistant fiber. Also, the separator is plain weave, twilled weave, or sateen weave fiber including the aforementioned fiber, or a fabric sheet such as nonwoven fabric or fabric available from a wet method, a span pond method, a melt blow method, a water flow leno weaving method, a needle punch method, a partial or total thermocompression method, or the like.