There are two routes in the opening of the pseudogap: one due to the band separation in a disordered system such as expanded liquid mercury and amorphous alloys and the other due to the Fermi surface-Brillouin zone interaction in quasicrystals and their approximants. The role of the pseudogap in the electron transport has been studied by plotting resistivities at 4.2 and 300 K against the electronic specific heat coefficient for a total of 49 quasicrystals and their approximants on the log-log diagram in comparison with those for the amorphous alloys. Among them, 32 data points are for sp-electron quasicrystals and their approximants like Al-Mg-Zn, Al-Li-Cu, Mg-Zn-Ga while 17 data points are for the Mackay icosahedral-type quasicrystals like Al-Cu-Fe and Al-Cu-Ru. All the data except for the Al-Pd-Re quasicrystal of high quality are found to fall on a straight line with a slope of -2. Whether or not the data for the Al-Pd-Re quasicrystal of high quality can be treated on the same footing is left for further investigation. From this we conclude that the resistivity changes in proportion to the square of the density of states (DOS) at the Fermi level in conformity with the Mott theory for all systems characterized by the pseudogap across the Fermi level.