PROBLEM TO BE SOLVED: To provide an oral formulation from which water-soluble medical ingredient is difficult to be eluted despite of long-term storage and which has excellent stability.SOLUTION: An oral formulation of the present invention is an oral formulation in which a capsule particle group (A) is dispersed into aqueous solution (B), in which said capsule particle group (A) is formed by allowing particles (a1) made of a water-soluble medical ingredient to be included in an enteric matrix (a2), and a volume median diameter is 100 to 1000 &mum. In said aqueous solution (B), concentration of at least one type of ingredient (b1) selected from inorganic salt, polyol and organic acid is 0.8 to 5.0 mol/L.
