Abstract: A nitric oxide administration device 14 includes a second flow path 201 including an intake port 201a and an NO supply port 201b, a discharge unit 205 which is arranged in the second flow path 201 and which generates NO from air introduced via the intake port 201a, generated NO being supplied via the NO supply port 201b, an NO2 adsorption unit 206 which is arranged downstream of the discharge unit 205 and removes NO2, a bypass flow path 217 for reflux from downstream of the NO2 adsorption unit 206 to upstream of the NO2 adsorption unit 206, and a three-way valve 216 for switching the opening and closing of a flow path from downstream of the NO2 adsorption unit 206 to the NO supply port 201b.