Patent attributes
A method of cultivating algal cells of an algae belonging to a class selected from Chlorophyceae, Euglenophyceae, Bacillariophyceae and Haptophyceae includes: irradiating the algal cells with an artificial light having a ratio of (i) photon flux density in a wavelength range of 520-630 nm to (ii) photosynthetic photon flux density, that is 65% or more; and measuring a condition of the algal cells and/or a condition of an algal cell culture provided by cultivating the algal cells. Irradiation and non-irradiation of the algal cells with the artificial light are switched, or the photon flux density in the wavelength range of 520-630 nm is changed, according to the measured condition of the algal cells and/or the measured condition of the algal cell culture.