Abstract: There are disclosed an apparatus for culturing plantlets by means of photoautotrophic growth, comprising principal constituents consisting essentially of a light transmittable and enclosed culture vessel 1, a carbon dioxide-rich air supply chamber 2 which is installed in contact with the bottom of the culture vessel, and a culture solution tank 3, wherein the supply chamber 2 is allowed to communicate with the culture vessel 1 through a plurality of vertical fine tubes, and the culture solution tank is connected to the culture vessel through tubing and is equipped with an air pump for supplying the culture vessel with the culture solution; and a process for culturing plantlets by means of photoautotrophic growth by the use of the above apparatus. The above apparatus and process can afford efficient and steady mass production of uniform nursery plants having an excellent degree of growth through a simple operation.