A novel particulate composite hydrotalcite which offers antacidic effect comparable to that of a particulate hydrotalcite so far used as a gastric antacid and, further, offers excellent stomach inner wall protection effect. A particulate composite hydrotalcite represented by the following formula (1), €ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ(Mg a Zn b ) 1-x Al x (OH) 2 (A n- ) x/n · mH 2 O€ƒ€ƒ€ƒ€ƒ€ƒ(1) wherein A n- is CO 3 2- , SO 4 2- or Cl - , n is 1 or 2, and x, a, b and m are values that satisfy the following conditions, 0.18 ‰¦ x ‰¦ 0.4 , 0.5 ‰¦ a <； 1 , 0 <； b ‰¦ 0.5 , 0 ‰¦ m <； 1 , and a gastric antacid using the particulate composite hydrotalcite as an effective component. When used as a gastric antacid, the particulate composite hydrotalcite suppresses the occurrence of damage in the mucous membranes of stomach and intestines.
