The energy distribution of output electrons (EDOE) from a channel electron multiplier was calculated theoretically for the unsaturated and the saturated operations. The theory is based on that of Yakobson on the gain characteristics of a channel electron multiplier. The theoretical result indicates that the half-width of EDOE under the unsaturated operation is larger than that under the saturated one. It is also found that the half-width depends on the field strength near the output of the channel. The experimental results are in good qualita-tive agreement with the theoretical results.