LDH SEPARATOR

There is provided an LDH separator including a porous substrate and a hydroxide ion-conductive layered compound that is a layered double hydroxide (LDH) and/or a layered double hydroxide (LDH)-like compound, filling up pores of the porous substrate. The proportion of the hydroxide ion-conductive layered compound in the LDH separator is 25 to 85% by weight.