1. An oral composition containing the following components (A) and (B) :( A) N-acyl acid amino acid or its salt in an amount of 0.005% by weight. or more and 0.3% of the mass. or less； and (B) pyrophosphoric acid or its salt in an amount of 0.005% of the mass. or more and 0.5% of the mass. or less, in which the mass ratio ((B) / (A)) of component (B) to component (A) is 0.05 or more and 40 or less, and the total content of component (A) and component (B) is 0 , 01% of the mass. or more and 0.6% of the mass. or less. 2. An oral care composition according to claim 1, wherein component (A) has an acyl group containing from 6 to 22 carbon atoms. The composition for caring for the oral cavity according to claim 1, additionally containing alkyl sulfate (C) in an amount of 0.5% of the mass. or more and 2% of the mass. or less. 4. The oral composition according to claim 3, wherein the mass ratio ((C) / (A)) of component (C) to component (A) is 5 or more and 200 or less. An oral care composition according to claim 1 or 2, wherein component (B) is pyrophosphoric acid or an alkali metal salt thereof. An oral composition according to claim 1 or 2, further comprising a non-ionic surfactant (F). 7. An oral care composition according to claim 6, wherein component (F) is one or more components selected from polyglycerol and fatty acid esters and sucrose and fatty acid esters. The composition for caring for the oral cavity according to claim 1 or 2, additionally containing sucralose (G) in an amount of 0.001% of the mass. or more and 0.1% of the mass. or less. 9. The oral composition according to claim 8, wherein the mass ratio of ((A) + (B)) / (G) of component (A) and component (B) to component (G) is 1 or more and 30 or less. 10. The oral composition according to claim 1 or 2, in which the total content of component (A) and component (B) is 0.02% of the mass. or more and 0.45% of the mass. or less. 11. The oral composition according to claim 1 or 2, wherein1. Состав для ухода за п
