A processing apparatus, comprises: a first acquirer configured to acquire a first specific information distribution of an object based on acoustic waves propagating from the object onto which light is irradiated； a second acquirer configured to acquire a characteristic value of the first specific information distribution of the object； a third acquirer configured to acquire information indicating a correspondence between an optical coefficient and the characteristic value of the first specific information distribution； and a fourth acquirer configured to acquire the optical coefficient of the object using the characteristic value of the first specific information distribution of the object and the information indicating the correspondence.
