The electron impact ionization coefficient and excitation coefficient for Xe (1s₄) in He-Xe (1, 2, 5, 10, 20, 50%) gas mixtures have been measured as functions of E/N by using a Steady State Townsend (SST) method. The ionization coefficient becomes larger than that of pure He and Xe when the amount of Xe is less than 10%, while the excitation coefficient of the 1s4 level of Xe increases as the Xe concentration increases. These experimental values have been compared with the results of Boltzmann equation analysis, and the contributions of individual atomic processes to the effective values have been discussed. The determined coefficients would be useful for a simulation of the gas discharge in a plasma display panel.