Provided is a layered-double-hydroxide-containing composite material including a porous substrate and a functional layer disposed on and/or in the porous substrate, the functional layer containing a layered double hydroxide represented by the formula M2+1−xM3+x(OH)2An−x/n.mH2O, where M2+ represents a divalent cation, M3+ represents a trivalent cation, An− represents an n-valent anion, n is an integer of 1 or more, and x is 0.1 to 0.4, and the functional layer further containing sulfur (S) at the interface between the functional layer and the porous substrate and in the vicinity of the interface. In the LDH-containing composite material of the present invention, the LDH-containing functional layer disposed on and/or in the porous substrate exhibits significantly improved conductivity.