A plant growing device (1) is provided with a ventilation unit (6) comprising an intake unit (61) for taking air into a growing chamber (R) and an exhaust unit (62) for exhausting air from the growing chamber (R). The intake unit (61) has an intake port (63), an intake damper (64) for opening and closing the intake port (63), a blower (65) for sending air in the direction of the growing chamber (R), a passage (66) for guiding air to the upstream side of the blower (65), and a circulation damper (67) for opening and closing the passage (66). The exhaust unit (62) has an exhaust port (68) and an exhaust damper (69) for opening and closing the exhaust port (68). The ventilation unit (6) operates under either an intake and exhaust mode for taking air into and exhausting air from the growing chamber (R) or a circulation mode in which air is caused to circulate in the growing chamber (R). By switching between these modes, CO2 is taken into the growing chamber (R) and gas density, temperature, and humidity within the growing chamber (R) can be made uniform, and as a result, the growing efficiency of a plant (P) can be improved.Le dispositif de culture de plantes (1) de linvention est équipé dune unité de ventilation (6) constituée dune unité dadmission dair (61) destinée à ladmission de lair dans une chambre de culture (R), et dune unité de décharge dair (62) destinée à la décharge de lair provenant de la chambre de culture (R). Lunité dadmission dair (61) possède : un orifice dadmission dair (63) un registre dadmission dair (64) ouvrant et fermant lorifice dadmission dair (63) une soufflante (65) soufflant dans la direction de la chambre de culture (R) un trajet (66) guidant lair en amont de la soufflante (65) et un registre de circulation (67) ouvrant et fermant le trajet (66). Lunité de décharge dair (62) possède : un orifice de décharge dair (68) et un registre de décharge dair (69) ouvrant et fermant lorifice de décharge dair (68). Lunité de ventilation (6) fonctionne
