To provide a yeast fermenting glucose as a main component of grape juice obtained from the natural world and furthermore fermenting maltose, whereas an inside leaven method having complicated processes has advantages that finished bread has excellent taste and is unlikely to harden and bread with high quality can be stably produced in factory production, and a microbial strain providing maltose-fermentative ability is used since sugar is not added in sponge dough as a raw material.

Cultured microbial cells of Saccharomyces cerevisiae NITE P-487 that has been isolated from a cherry of Prunus sargentii that grows naturally in Tokachi area in Hokkaido are used. The Saccharomyces cerevisiae NITE P-487 has strong maltose-fermentative ability. Bread with high quality and characteristic and good taste can be produced using the cultured microbial cells.