The present invention provides an oral cavity composition with which brief treatment using the same yields a high effect for dental cavity prevention and an excellent dental hyperesthesia preventive and treatment effects, and a method of treatment using such a composition. The oral cavity composition according to the present invention contains a first composition (A) containing a fluoride ion-supplying compound, an inorganic phosphoric acid and a salt thereof, and a second composition (B) containing a calcium salt of organic acid, with an organic acid constituting said calcium salt of organic acid having a pKa value ranging from 3 to 11, or at least one pKa value ranging from 3 to 11 when said organic acid has plural pKa values, wherein said first composition (A) and said second composition (B) are discretely packed from each other so that said two compositions can be alternately used and then come to be mixed with each other at a tooth region when applied thereto.
