1. The differentiation process of the cluster cells of compound eye in wild typed Drosophila melanogaster, born in Heuk San Do, Korea, was observed. 2. The eye disc of Drosophila melanogaster is originated from the frontal sac before hatching. 3. Clusteris bgin to form at the posterior end of the eye disc at the 2 nd instar larval stage, and the completed to differentiate in the eye disc at the 96 hours after hatching . 4. At the pupa stage, the eye cups are formed by clusters. 5. The eye cup begins to elongate and is changed into an ommatidium. 6. All organs of an ommatidium are completed in an omatidium at the old pupa stage(156-160 hours after hatching. )