Homogeneously fullerene-dispersed membranes were prepared under the conditions in which a 10 wt % poly(1-trimethylsilyl-1-propyne) solution containing 0.5 wt % fullerene was dried under a reduced pressure of 50 cmHg at 100 degrees C. UV-vis spectra and microscopic observations of the fullerene membranes indicated that the fullerene was homogeneously dispersed in the membranes. The permeability coefficients of 1-butene were found to be higher than those of n-butane in the fullerene membranes, although the permeability coefficients of olefin gases were nearly equal to those of paraffin gases having the same number of carbon in poly(1-trimethylsilyl-1-propyne) membranes containing no fullerene. Pressure dependence of permeability coefficients was clearly observed for the permeation of carbon dioxide, ethylene, ethane, 1-butene, and n-butane through the fullerene membranes, while no significant dependence was found for poly(1-trimethylsilyl-1-propyne) membranes except for the permeation of 1-butene and n-butane. The pressure dependence of the permeability was explained by the dual-mode sorption model.