A blood storage container suitable for quick and efficient production of a large amount of serum while ensuring high safety, and a method of separating blood and a regenerative medical process using the same are provided. In a blood component separator 1 for separating collected blood into a plurality of blood components and preserving them, the separator 1 including a blood reservoir 10 for reserving the blood and a component storage part 20 aseptically connected in an air-tight manner to this blood reservoir 10, to the aforementioned blood reservoir 10 being imparted a serum producing function to remove coagulation factors from the blood to an extent enabling use in practical applications as a serum, and the aforementioned component storage part 20 storing each blood component generated by separation of the blood in the blood reservoir 10.