PURPOSE: A bottle cap is provided to smoothly inflow oxygen to the human body through the airway by forming an upper space and a side space on an upper cap. CONSTITUTION: A bottle cap comprises the following: a receiving unit(20) installed in the inside a main body(10); a discharging supporter(30) with the lower side blocking an opening and closing hole formed on the lower side of the receiving unit; an upper bulbous unit combined with the lower side of the discharging supporter; an upper cap(40) for opening and closing, combined with the discharging supporter; an upper space(41) and a side space(42) formed on the upper cap; and a hole(43) penetrating the upper cap.
