In a step of producing a powder product of the alga belonging to the genus Dunaliella, the present invention includes a pH adjusting step in which an alga belonging to the genus Dunaliella is allowed to be in a basic state of pH 9.5 or higher. According to the method, it is possible to provide dried Dunaliella powder containing (3-carotene at a high content by suppressing degradation of (3-carotene as an active ingredient while decreasing each of the total pheophorbide amount and the existing pheophorbide amount to a predetermined value or less, even if the total pheophorbide amount and the existing pheophorbide amount of the cultured algae belonging to the genus Dunaliella are higher in summer. [Selective Figures] none
