Abstract: A process for producing an antimicrobial compound represented by the following formula [1]:M.sup.1.sub.a H.sub.b A.sup.1.sub.c M.sup.2.sub.2 (PO.sub.4).sub.3.nH.sub.2 O [1]wherein M.sup.1 is at least one metal ion selected from silver, copper, zinc, tin, mercury, lead, iron, cobalt, nickel, manganese, arsenic, antimony, bismuth, barium, cadmium and chromium, A.sup.1 is at least one ion selected from alkali metal ion and alkaline earth metal ion, M.sup.2 is a tetravalent metal, n is a number which satisfies 0.ltoreq.n.ltoreq.6, a and b are positive numbers and c is 0 or a positive number, and a, b and c satisfy ka+b+mc=1 where k is a valence of M.sup.1 and m is a valence of A.sup.1, by supporting at least one metal ion selected from silver, copper, zinc, tin, mercury, lead, iron, cobalt, nickel, manganese, arsenic, antimony, bismuth, barium, cadmium and chromium on a phosphate represented by the following formula [2]:A.sup.2.sub.d M.sup.2.sub.2 (PO.sub.4).sub.3.nH.sub.2 O [2]wherein A.sup.