One object of the present invention is to provide an air separation method and an air separation apparatus which can collect a larger amount of nitrogen gas, liquefied oxygen, and liquefied nitrogen which have higher pressure than the operating pressure in the low-pressure column while inhibiting a decrease of the argon recovery, and the present invention provides an air separation method comprising a step in which the low-pressure liquefied oxygen at the bottom part of the low-pressure column is reboiled by the argon gas at the top part of the argon column and the middle-pressure nitrogen gas at the top part of the middle-pressure column, and a step in which the middle-pressure liquefied oxygen at the bottom part of the argon column is reboiled by the high-pressure nitrogen gas at the top part of the high-pressure column.