A process for forming a fine pattern comprised of a polyhydroxyalkanoate on a substrate is provided. The process comprises steps of applying a polyhydroxyalkanoate-synthesizing enzyme and a 3-hydroxyacyl CoA to coexist in an intended pattern on a substrate, and polymerizing the 3-hydroxyalkanoate by action of the enzyme to form the polyhydroxyalkanoate in a pattern on the substrate. In particular, the fine pattern can be formed by an inkjet system.