As a means for increasing the yield of carbon nanotubes produced by gas-phase catalysis, provided is a production device (10) for producing carbon nanotubes by gas-phase catalysis that is characterized by being provided with: a first chamber (14) that has a growth region that is a region where carbon nanotubes are formed; first temperature adjustment devices (16, 18) that can adjust the temperature of the growth region inside the first chamber (14); pressure adjustment devices (23, 24) that can adjust the pressure inside the first chamber (14); a first supply device (30) that can supply a carbon source to the growth region inside the first chamber (14); and a first vaporization device (including a heater (31B)) that can vaporize a fluid (L) that is disposed inside the production device (10). The production device is also characterized in that the first vaporization device (which includes the heater (31B)) can vaporize the fluid (L) such that at least one type of gas-phase catalyst that is formed from an iron-group-element-containing substance and a halogen-containing substance that are contained in the fluid (L) is supplied to the growth region inside the first chamber (14).