Influence of hardener stoichiometry in epoxy resin on space charge accumulation characteristics were investigated using PEA (pulsed electro-acoustic) method at high temperature under high electric field. In previous study, it was found that the space charge accumulation was observed in epoxy resin at high temperature under high electric stress just before electric breakdown, and the space charge accumulation is important to understand the breakdown. Since the origin of the space charge was assumed to be ions generated from impurities included in epoxy resin. Since the residual hardener of epoxy resins or unbound monomers can be a source of ions, the space charge accumulation characteristics were examined using epoxy resins prepared with varying amount of hardener. Judging from the experimental results, it was not clear whether the addition of excessive hardener or lack of hardener would cause space charge accumulation as well as reduce the insulating properties of epoxy resin itself.