PURPOSE: To improve the stability of tank level control.

CONSTITUTION: This controller is provided with a low-level movement setting circuit 14 for setting the set low position of a low liquid level setting circuit 12 lower just for previously decided low-level set width by activating a pouring pump, high-level mode setting circuit 15 for setting the set high position of a high liquid level setting circuit 13 lower just for previously decided high-level set width after the lapse of predetermined time from the start of the pouring pump 4, high-level recovery setting circuit 16 for returning the set position of the high liquid level setting circuit 15 to the set high position by stopping the pouring pump 4, and low-level recovery setting circuit 17 for returning the set position of the low liquid level setting circuit 12 to the set low position after the lapse of predetermined time from the stop of the pouring pump 4.