We have measured positron annihilation lifetime spectra and discuss the first shell of atomic cluster in quasicrystal Zn-Mg-Sc and the approximant crystal Zn(17)Sc(3) by comparing with Cd-Yb icosahedral quasicrystals and the approximant crystal Cd(6)Yb. These measurements suggested that vacancy-like open space might exist around the first shell of atomic cluster.