The present invention provides a soy milk fermented substance having the same flavor and smooth properties as yogurt obtained through the lactic fermentation of milk without performing a processing treatment such as an enzyme treatment or an extraction treatment on soy milk used as a raw material, and without adding a raw material such as a sugar source, even when only streptococcus thermophilus and lactobacillus delbrueckii subsp. bulgaricus are used as a lactic acid-mixed starter when a fermented substance for which soy milk is used as a raw material is produced. The soy milk fermented substance obtained using a lactic acid-mixed starter including streptococcus thermophilus and lactobacillus delbrueckii subsp. bulgaricus. The streptococcus thermophilus is capable of accumulating 0.4 g/L or more of lactose in a fermented substance when inoculated into soy milk and cultivated. The lactobacillus delbrueckii subsp. bulgaricus is capable of accumulating 0.4 g/L or more of D-lactic acid in a fermented substance when inoculated into soy milk and cultivated.
