The present invention relates to a stable astaxanthin-containing powdery composition which is obtained by drying a suspension containing a ground Haematococcus alga containing astaxanthin, a surfactant, an antioxidant, an excipient and water and to a process for preparing the same.According to the present invention, there can be provided an astaxanthin-containing powdery composition wherein astaxanthin present in Haematococcus alga has been efficiently stabilized to improve its storage stability for a long term and which is excellent in flowability as a powder, easy to handle and can be easily subjected to solvent extraction without degrading the astaxanthin.