A substrate processing apparatus comprising: a processing chamber which is to accommodate at least one substrate; a gas supply system which is to supply processing gas into the processing chamber; an exhaust system which is to exhaust atmosphere in the processing chamber; and at least one pair of electrodes which are to bring the processing gas into an active state and which are accommodated in protection tubes such that the electrodes can be inserted into and pulled out from the protection tubes, wherein the electrodes are accommodated in the protection tube in a state where at least a portion of the electrodes is bent, and the electrodes are formed of flexible members, is disclosed.