A substrate processing apparatus includes a processing chamber for accommodating therein a processing target substrate; a gas exhaust path through which a gas inside the processing chamber is exhausted; one or more exhaust pumps provided in the gas exhaust path; and a scrubber for collecting harmful components from an exhaust gas. The apparatus further includes an ionized gas supply unit for supplying to the gas exhaust path an ionized gas for neutralizing charged particles included in the exhaust gas flowing therethrough.