In a continuous regeneration type exhaust gas post-processing apparatus equipped with an oxidation catalyst (DOC) and a diesel particulate filter (DPF), reliably removing particulate matter (PM) deposited to the DOC for maintaining the activity performance of DOC. The present invention relates to a method of forcibly regenerating a continuous regeneration type exhaust gas post-processing apparatus installed in an engine-driven generator equipped with a generator body driven by a diesel engine. When the engine is in a predetermined light load running state during forced regeneration in which intake gas to the engine is restricted to increase a temperature of exhaust gas, a heater actuated with electricity generated by the generator body switches ON in order to increase a load on the engine and thus a DOC inlet temperature of the exhaust gas post-processing apparatus to a burning temperature of PM deposited in the DOC or more.