A method of producing frozen dough for bread containing a filling, the method comprising: preparing a dough comprising flour, salt, baking improvers, sugar, eggs and water; dividing the dough into pieces; inserting a filling into the dough piece and enclosing the resulting dough; and freezing the filling-containing dough; the method is characterized in that the preparation of the dough comprises: preparing a first dough by mixing some of the flour at 55% by weight, some of the salt at 0.2% by weight, 0.5% by weight of yeast, any of the baking improvers at 0.3% by weight, 42% by weight of milk and some of the water at 2% by weight and kneading the mixture at a speed of 90 rpm for 10 to 20 minutes; subjecting the first dough to fermentation at room temperature for 1 to 3 hours and storing the first dough in a refrigerator maintained at a temperature in a range of 0 to 10°C for 12 to 15 hours, to prepare a sponge dough; preparing a second dough by mixing the sponge dough with raw materials including the remaining flour at 45% by weight, the sugar at 15% by weight, the remaining salt at 1.5% by weight, the eggs at 15% by weight, the remaining baking improvers at 0.5% by weight, 5% by weight of butter, the remaining water at 6% by weight and 2% by weight of yeast and kneading at a speed of 90 rpm for 2 to 5 minutes, then 10% by weight of butter is further added to the resultant product and kneaded again at a speed of 90 rpm for 4 to 5 minutes; subjecting the second dough to fermentation for 60 to 70 minutes at a temperature in a range of 28 to 35°C and humidity of 70 to 95%; the division into pieces is made on the firstly fermented dough and each pieces weighs 40 g to 60 g; leaving the fermented dough pieces to be benched for a bench time of 5 to 15 minutes; the filling is a red bean filling and 20 to 40 g of the red bean filling is inserted into the each benched dough piece; the filling-containing dough is frozen at a temperature of -18°C preparing a dough comprising flour, salt, baking improvers, sugar, eggs and water; dividing the dough into pieces; inserting a filling into the dough piece and enclosing the resulting dough; and freezing the filling-containing dough; the method is characterized in that the preparation of the dough comprises: preparing a first dough by mixing some of the flour at 55% by weight, some of the salt at 0.2% by weight, 0.5% by weight of yeast, any of the baking improvers at 0.3% by weight, 42% by weight of milk and some of the water at 2% by weight and kneading the mixture at a speed of 90 rpm for 10 to 20 minutes; subjecting the first dough to fermentation at room temperature for 1 to 3 hours and storing the first dough in a refrigerator maintained at a temperature in a range of 0 to 10°C for 12 to 15 hours, to prepare a sponge dough; preparing a second dough by mixing the sponge dough with raw materials including the remaining flour at 45% by weight, the sugar at 15% by weight, the remaining salt at 1.5% by weight, the eggs at 15% by weight, the remaining baking improvers at 0.5% by weight, 5% by weight of butter, the remaining water at 6% by weight and 2% by weight of yeast and kneading at a speed of 90 rpm for 2 to 5 minutes, then 10% by weight of butter is further added to the resultant product and kneaded again at a speed of 90 rpm for 4 to 5 minutes; subjecting the second dough to fermentation for 60 to 70 minutes at a temperature in a range of 28 to 35°C and humidity of 70 to 95%; the division into pieces is made on the firstly fermented dough and each pieces weighs 40 g to 60 g; leaving the fermented dough pieces to be benched for a bench time of 5 to 15 minutes; the filling is a red bean filling and 20 to 40 g of the red bean filling is inserted into the each benched dough piece; the filling-containing dough is frozen at a temperature of -18°C preparing a first dough by mixing some of the flour at 55% by weight, some of the salt at 0.2% by weight, 0.5% by weight of yeast, any of the baking improvers at 0.3% by weight, 42% by weight of milk and some of the water at 2% by weight and kneading the mixture at a speed of 90 rpm for 10 to 20 minutes; subjecting the first dough to fermentation at room temperature for 1 to 3 hours and storing the first dough in a refrigerator maintained at a temperature in a range of 0 to 10°C for 12 to 15 hours, to prepare a sponge dough; preparing a second dough by mixing the sponge dough with raw materials including the remaining flour at 45% by weight, the sugar at 15% by weight, the remaining salt at 1.5% by weight, the eggs at 15% by weight, the remaining baking improvers at 0.5% by weight, 5% by weight of butter, the remaining water at 6% by weight and 2% by weight of yeast and kneading at a speed of 90 rpm for 2 to 5 minutes, then 10% by weight of butter is further added to the resultant product and kneaded again at a speed of 90 rpm for 4 to 5 minutes; subjecting the second dough to fermentation for 60 to 70 minutes at a temperature in a range of 28 to 35°C and humidity of 70 to 95%; the division into pieces is made on the firstly fermented dough and each pieces weighs 40 g to 60 g; leaving the fermented dough pieces to be benched for a bench time of 5 to 15 minutes; the filling is a red bean filling and 20 to 40 g of the red bean filling is inserted into the each benched dough piece; the filling-containing dough is frozen at a temperature of -18°C