Abstract: This nitrogen oxide concentration measurement device measures a nitrogen oxide concentration by shining light on a sensor produced by distributing a metal complex of porphyrin or a derivative thereof over a base material, and detecting the amount of light of a specific wavelength, said device comprising a light source that shines light at a nitrogen oxide concentration measurement sensor, a light detector that detects the amount of light of a specific wavelength out of all the light transmitted or reflected by the nitrogen oxide concentration measurement sensor, and a controller that corrects the detection result at the light detector so as to match the amount of light of a specific wavelength outputted from the light detector during exposure to a zero gas to a corrected value.

Abstract: A nitrogen oxide concentration measurement device comprises a zero scrubber disposed within a gas flow path, and a controller. The zero scrubber performs subjects exhaled air flowing through the gas flow path from a mouthpiece toward a chamber to a NO removal treatment in a first period, out of a first period and a second period. The controller acquires the concentration of NO contained in the exhaled air on the basis of the differential voltage value outputted in the second period, which uses as a reference the differential voltage value outputted in the first period.