Provided is a laxative tablet which includes magnesium oxide as a main constituent, wherein (1) the particle size by volume of 50% (D50) of particles which emerge when the tablet is suspended in water is 70 μm or less as determined by laser diffractometry, (2) the particle size by volume of 90% (D90) of the particles which emerge when the tablet is suspended in water is 130 μm or less as determined by laser diffractometry, and (3) the dissolution time of the tablet when the tablet is suspended in water according to the Japanese Pharmacopoeia—general testing methods—dissolution testing methods is 10 seconds or less.