To provide a method for improving bread dough in order to increase the volume of the dough and for obtaining high quality bread excellent in an outward appearance, an internal phase and flavor in producing bread.

High quality bread having a larger volume and excellent in an outward appearance, an internal phase and flavor can be produced by making bacterial strains such as a lacto bacillus and an Acetobacter bacillus having ability to produce acetic acid, yeast or their fermented products exist in the dough composed mainly of wheat flour and containing and/or not containing baker's yeast to cause and promote the aging of the dough. Further, in addition to improvement in the physical properties of the dough, it is possible to shorten fermentation (aging) time and also to shorten process time in producing bread.