Abstract: The measurement of energy spectra of ion beams from the gas – puff Z – pinch plasma device has been carried out in this study by employing the compact Thomson ion energy analyzer developed recently by us. Clear parabolic tracks of Ar+ , Ar2+, Ar3+ ions on CR-39 plastics and energy spectra of these ions have been obtained. The results show that the maximum ion energy is about 1MeV, ion energy spectrum distributions are expressed approximately by dN / dT /dw T-2.