The present invention relates to a process for producing zeaxanthin, .beta.-carotene, or lycopene, comprising inducing mutation in a carotenoid-producing microorganism in which the base sequence of DNA corresponding to 16S ribosomal RNA is substantially homologous to the base sequence described in SEQ ID NO: 1; screening for a mutant strain having a high product proportion of zeaxanthin, .beta.-carotene, or lycopene to the whole production amount of carotenoids to provide a microorganism producing zeaxanthin, .beta.-carotene, or lycopene; culturing the mutant microorganism; and harvesting zeaxanthin, .beta.-carotene, lycopene or a carotenoid mixture containing the same from the resultant culture.