Abstract: A method and an apparatus for separating a specific component gas from a mixed gas, wherein granular adsorbent is held in a sealed space in a layered state, easily adsorptive gas is adsorbed to the granular adsorbent by blowing material mixed gas into the adsorbent layers and contacting the granular adsorbent with a counter-current of material gas, and the granular adsorbent is transferred gradually out of the sealed space, and reactivated by desorbing the easily adsorptive gas from the granular adsorbent, and the reactivated granular adsorbent is returned to the inside of the sealed space to be reused. Therefore, frequent actions of opening and closing valves are unnecessary, so that it is possible to separate and produce excellent product gas with high purity.