A new technique of superwide pressure range adsorption (SWPA) isotherm measurement of N-2 from P/P-0 = 10(-9) to 1 at 77 K was developed. The superwide pressure range adsorption isotherms of N-2 on activated carbon fiber, molecular sieve carbon, and carbon black were compared with those of their ordinary pressure range isotherms and the simulated isotherms calculated with grand canonical Monte Carlo technique. The SWPA measurement can show the adsorption uptake below P/P-0 = 10(-6), which is assigned to the adsorption in ultramicropores of pore width < 0.7 nm. The SWPA method shows the presence of ultramicropores even for nonporous carbon black, which has been believed to be nonporous from the ordinary adsorption measurement. Thus, the SWPA method can elucidate the ultramicropore structures of less-crystalline materials.