A nozzle device which can perform accurate quantitative suction without being affected by a pressure when, for example, a nozzle (2) is inserted into a closed container (T). The nozzle device has the nozzle (2) that is inserted into the closed container(T) and that sucks a liquid in the closed container (T), an exposure to atmosphere mechanism (3) that opens the closed container (T) to the atmospheric air, and an opening/closing structure (4) that is arranged at a proximal end of the nozzle (2) and that has an internal flow channel (411) communicated with a flow channel in the nozzle (2) and an opening/closing mechanism for opening and closing the internal flow channel (411), and an opening/closing control section (5) that controls the opening/closing mechanism.