A novel cell culture medium suitable for primary culture of insect cells, an insect-derived water-soluble chitin, and a process of preparing an insect culture cell line in a short period of time by using the insect primary culture medium and the insect-derived water-soluble chitin. The insect cell primary culture medium comprises lactalbumin hydrolysate, yeastolate, and tryptose phosphate broth as protein extracts, and polyvinylpyrrolidone as a viscosity-supplementing agent. The insect-derived water-soluble chitin is subjected to deacetylation as the sole chemical modification.