To provide a preparation capable of easily and efficiently improving the quality of filling-containing breads, in particular, filling-containing breads in which the amount of filling is comparatively large and/or the water content in the filling is high, and a production method, and the like, for breads using the preparation. By adding and mixing an alginate ester, powdered egg yolk, and modified starch in bread dough for filling-containing breads, the migration of moisture from the filling to the bread part is suppressed and sogginess of the bread in such breads is suppressed even if there is a migration of moisture, peeling of the bread crust is suppressed, sticking of the bread is suppressed, and the bread is imparted with a flaky texture, as a result of which the bread quality can be improved.
