Provided is a technology which is capable of more accurately diagnosing chronic obstructive pulmonary disease (COPD), even without measuring the carbon dioxide concentration in arterial blood. This expired air examination system 100 is provided with an expired air examination device 1, and a device main body 51 which is connected to the expired air examination device 1 so as to be capable of communicating therewith. The expired air examination device 1 is provided with: a flow path-forming member provided with a flow path through which expired air from a subject flows a gas sensor provided with a light emission unit which emits infrared radiation into the flow path, and a light reception unit which receives the infrared radiation emitted by the light emission unit and a mouthpiece which is connected to the flow path-forming member in a state of communicating with the flow path. The device main body 51 is provided with: a measurement unit 52 which, on the basis of an electrical signal outputted from the gas sensor, measures the carbon dioxide concentration included in the expired air from the subject an extraction unit 60 which extracts the maximum carbon dioxide concentration from the measurement results of the measurement unit which were obtained in a period in which the subject respired N times (N being an integer equal to or greater than 2) and a display unit 57 for displaying the maximum carbon dioxide concentration extracted by the extraction unit 60.本發明之課題在於提供一種即使不測定動脈血中之二氧化碳濃度,仍可更正確地進行COPD之診斷之技術。本發明解決手段之呼氣檢查系統100,其具備呼氣檢查裝置1、及可通信地連接於呼氣檢查裝置1之裝置本體51。呼氣檢查裝置1係具備:流路形成構件,其具有用以供被檢者之呼吸氣流動之流路;氣體感測器,其具有朝流路出射紅外線之發光部、及接收發光部出射之紅外線之受光部;及吹嘴,其在連通於流路之狀態下被連接於流路形成構件。裝置本體51係具備:測量部52,其根據自氣體感測器輸出之電信號,測量被檢者之呼氣中含有之二氧化碳濃度;擷取部60,其根據於被檢者進行N次(N為2以上之整數)呼吸之期間獲得之測量部之測量結果,擷取二氧化碳濃度之最大值;及顯示部57,其用以顯示以擷取部60擷取之二氧化碳濃度之最大值。1‧‧‧呼氣檢查裝置51‧‧‧裝置本體100‧‧‧呼氣檢查系統
