An antacid and laxative tablet comprising magnesium oxide particles as an effective component, wherein (i) the magnesium oxide particles contained in the tablet have an average secondary particle diameter measured by a laser diffraction scattering method of 0.5 to 10 .mu.m, (ii) the content of magnesium oxide particles in the tablet is 88 wt % or more, (iii) the tablet does not become blackish and has substantially no tableting spot, and (iv) the disintegration time is 10 sec or less.The antacid and laxative tablet of the present invention has a high content of magnesium oxide particles, a short disintegration time, does not become blackish, has no tablet trouble and no tableting spot and is suitably administered orally.