In this study, in order to evaluate the insulation performance of spacecraft surface insulating materials when they are irradiated with electron beams under charged conditions, space charge distribution was measured using the pulsed electroacoustic method by applying a DC voltage to the insulating materials while irradiating them with electron beams. As a result, the charge accumulation within the material was observed immediately after the electron beam irradiation, with charge accumulation occurring at positions corresponding to the calculated penetration depth of the irradiating electrons. Consequently, localized electric field enhancement was observed in the non-irradiated regions, reaching electric field values that could potentially lead to insulation breakdown. These findings suggest the significance of not only surface charge evaluation but also internal charge evaluation in the design of spacecraft.