An array device including a base having wells, a cover positioned over the base with a gap from the base such that openings of the wells are covered by the cover with the gap in between, an injection port communicating with the gap, a discharge port communicating with the gap and positioned apart from the injection port, and a waste liquid vessel which collects liquid that flows from the gap via the discharge port and is positioned at a level different from the gap forming a channel. The discharge port is placed to discharge a surplus aqueous solution outside the wells from the discharge port by an oleaginous sealing liquid to be delivered from the injection port.