To enable setting up a timer time for automatic run easily in a plasma surface-treatment device which performs the surface treatment of a material by a plasma generated by arc discharge.

In a 'continue' mode which an arc discharge continues until a stop operation is performed, a CPU clocks a processing time from the start of arc discharge to a stop, and makes to display it on a timer display part (step 408). If a pushing of a memory switch is continued for 2 seconds, the processing time will be memorized by a memory (step 409). By switching to a timer mode and pushing a memory switch, one of two or more memorized processing times is read, and it is set to a timer. If the arc discharge is started with the start switch or a trigger signal, the timer display will count it down And when it becomes zero, the arc discharge is stopped automatically.