A method for separating a blast furnace gas containing carbon dioxide, nitrogen, hydrogen, and carbon monoxide, comprising: a first pressure swing adsorption gas separation step for repeating a cycle including a first adsorption step and a first desorption step, based on a pressure swing adsorption gas separation method that uses a first adsorption tower filled with a first adsorbent that preferentially adsorbs carbon dioxide, the first adsorption step comprising: introducing a blast furnace gas to the first adsorption tower to allow carbon dioxide in the blast furnace gas to absorb onto the first adsorbent, and discharging a first unadsorbed gas from the adsorption tower, the first desorption step comprising: allowing carbon dioxide to desorb from the first adsorbent and discharging a desorbed gas to outside the tower, a second pressure swing adsorption gas separation step for repeating a cycle including a second adsorption step and a second desorption step, based on a pressure swing adsorption gas separation method that uses a second adsorption tower filled with a second adsorbent that preferentially adsorbs carbon monoxide, the second adsorption step comprising: introducing the first unadsorbed gas into the second adsorption tower to allow carbon monoxide in the first unadsorbed gas to adsorb onto the second adsorbent, and discharging a second unadsorbed gas from the adsorption tower, the second desorption step comprising: allowing carbon monoxide to desorb from the second adsorbent and discharging a desorbed gas to outside the tower, wherein a gas discharged from the start of the first adsorption step up to a particular point of time is recovered through a hydrogen recovery pipe from the first unadsorbed gas discharged from the first adsorption tower in the first adsorption step. a first pressure swing adsorption gas separation step for repeating a cycle including a first adsorption step and a first desorption step, based on a pressure swing adsorption gas separation method that uses a first adsorption tower filled with a first adsorbent that preferentially adsorbs carbon dioxide, the first adsorption step comprising: introducing a blast furnace gas to the first adsorption tower to allow carbon dioxide in the blast furnace gas to absorb onto the first adsorbent, and discharging a first unadsorbed gas from the adsorption tower, the first desorption step comprising: allowing carbon dioxide to desorb from the first adsorbent and discharging a desorbed gas to outside the tower, a second pressure swing adsorption gas separation step for repeating a cycle including a second adsorption step and a second desorption step, based on a pressure swing adsorption gas separation method that uses a second adsorption tower filled with a second adsorbent that preferentially adsorbs carbon monoxide, the second adsorption step comprising: introducing the first unadsorbed gas into the second adsorption tower to allow carbon monoxide in the first unadsorbed gas to adsorb onto the second adsorbent, and discharging a second unadsorbed gas from the adsorption tower, the second desorption step comprising: allowing carbon monoxide to desorb from the second adsorbent and discharging a desorbed gas to outside the tower, wherein a gas discharged from the start of the first adsorption step up to a particular point of time is recovered through a hydrogen recovery pipe from the first unadsorbed gas discharged from the first adsorption tower in the first adsorption step.