To efficiently obtain astaxanthin carotenoid pigment from an alga on an industrial scale by breaking the cell walls of an alga Haematococcus prabiaris by the application of a turbulent flow under high pressure, drying the broken cell walls and extracting them with an organic solvent.

An alga slurry containing 5-10wt.% solid matter is introduced into a pressure pipe kept at a pressure of at least 2,000psi, desirably 3,000-6,000psi, and transferred to an interaction chamber kept at a pressure higher than 10,000psi, desirably 11,000-23,000psi, whereupon the slurry passes at an accelerated speed to cause a turbulent flow. This flow breaks the cell walls of the alga to reduce substantially the particle of the particles of the alga. If required, the slurry is recirculated through the apparatus. This causes the break of 95% or more of the cell walls of the alga. After the cells of the alga disintegrated by the treatment are dried, the dried cells are extracted with an organic solvent (e.g. methylene chloride) to recover the pigment. An antioxidant (e.g. BHA) may be added to the system of extraction.