PROBLEM TO BE SOLVED: To provide a CO2 supply device and a duct hood that prevent a combustion failure from occurring in a combustor even when a fan for feeding a combustion gas containing CO2 into the cultivation room is defective. SOLUTION: The CO2 supply device 1 includes a combustor 102, an air supply port 118a and an exhaust port 119a, an air supply duct 118, an exhaust duct 119, and a duct hood 210 that covers the air supply port 118a and the exhaust port 119a. And a supply duct 220 for guiding the combustion gas and a supply fan 221 for taking the combustion gas into the supply duct 220. Each of the side walls 213a to 213d of the duct hood 210 has an air inside the duct hood 210. Of the side walls 213a to 213d, the opening 214a provided to the side wall 213a closest to the air supply port 118a is the opening provided to the other side walls 213b to 213d. It opens closer to the top wall 212 than 214b to 214d. [Selection diagram] Fig. 4【課題】栽培室内にＣＯ２を含む燃焼ガスを送り込むためのファンに不具合が生じた場合でも、燃焼器に燃焼不良を生じさせないようなＣＯ２供給装置、およびダクトフードを提供する。【解決手段】ＣＯ２供給装置１は、燃焼器１０２と、給気口１１８ａおよび排気口１１９ａと、給気ダクト１１８と、排気ダクト１１９と、給気口１１８ａと排気口１１９ａとを覆うダクトフード２１０と、燃焼ガスを導くための供給ダクト２２０と、供給ダクト２２０に燃焼ガスを取り込むための供給ファン２２１と、を備え、ダクトフード２１０の側壁２１３ａ～２１３ｄのそれぞれには、ダクトフード２１０内に空気を取り込むための開口部２１４ａ～２１４ｄが設けられており、側壁２１３ａ～２１３ｄのうち、給気口１１８ａに最も近い側壁２１３ａに設けられる開口部２１４ａは、他の側壁２１３ｂ～２１３ｄに設けられる開口部２１４ｂ～２１４ｄよりも天壁２１２の近くまで開口する。【選択図】図４
