PROBLEM TO BE SOLVED: To provide a lettuce cultivation system and method fulfilling conditions for attaining the head formation of lettuces by combining existing technologies and performing total control to create an outdoor raising environment.SOLUTION: The lettuce cultivation system includes a cultivation vessel 11, a water supply vessel 20, a fertilizer tank 21, a CO2 tank 18, a light source 13, an air conditioner 14, a fan 15, various sensors, a CO2 sensor 17, and a controller 2. The controller 2 controls a water supply state to the cultivation vessel 11, controls the CO2 tank 18 so that the CO2 concentration is higher than that of outdoor cultivation, periodically controls the light source 13 to repeat a light period and a dark period in a shorter period than the period in outdoor cultivation, and controls the air conditioner 14 and the fan 15 so that an environmental temperature and an air current vary.
