A culture device comprising: a culture bag with flexibility which has a port (73,74) through which a liquid flows and enables cell culture in an internal space; a bag holding portion having holding plates (42, 43) which sandwich the culture bag and a rotating shaft (48,49); a rotation mechanism supporting and rotating the rotating shaft; a liquid supply/discharge mechanism supplying and discharging a liquid to/from the culture bag; and a rotation control portion controlling rotation of the rotation mechanism, a culture control portion configured for outputting a first information and a second information to the rotation control portion, wherein when a culture step is performed, the culture control portion outputs the first information to the rotation control portion, and when a solution exchanging step is performed, the culture control portion outputs the second information to the rotation control portion and drives the liquid supply/discharge mechanism to partially or completely exchange a solution in the culture bag, the rotation control portion being configured for bringing the culture bag holding portion into a first position in which a supporting surface (65, 66) supporting the culture bag in the holding plates (42, 43) is in parallel with an approximately horizontal direction according to the first information indicating that cell culture is performed in the culture bag, and for bringing the bag holding portion into a second position in which the supporting surface (65,66) is neither parallel with the horizontal direction nor with a vertical direction when a solution in the culture bag is caused to flow out of the port according to a second information indicating that solution exchange is performed in the culture bag. a culture bag with flexibility which has a port (73,74) through which a liquid flows and enables cell culture in an internal space; a bag holding portion having holding plates (42, 43) which sandwich the culture bag and a rotating shaft (48,49); a rotation mechanism supporting and rotating the rotating shaft; a liquid supply/discharge mechanism supplying and discharging a liquid to/from the culture bag; and a rotation control portion controlling rotation of the rotation mechanism, a culture control portion configured for outputting a first information and a second information to the rotation control portion, wherein when a culture step is performed, the culture control portion outputs the first information to the rotation control portion, and when a solution exchanging step is performed, the culture control portion outputs the second information to the rotation control portion and drives the liquid supply/discharge mechanism to partially or completely exchange a solution in the culture bag, the rotation control portion being configured for bringing the culture bag holding portion into a first position in which a supporting surface (65, 66) supporting the culture bag in the holding plates (42, 43) is in parallel with an approximately horizontal direction according to the first information indicating that cell culture is performed in the culture bag, and for bringing the bag holding portion into a second position in which the supporting surface (65,66) is neither parallel with the horizontal direction nor with a vertical direction when a solution in the culture bag is caused to flow out of the port according to a second information indicating that solution exchange is performed in the culture bag.