A passive component structure includes an insulating substrate having a centered hollow portion and provided on a surface with a coil holding zone having at least one spiral receiving recess; at least one coil held in the coil holding zone and including a winding portion received in the spiral receiving recess and connected to a first and a second terminal; an insulating encapsulation member covering at least the insulating substrate and the winding portion of the coil; and a magnetic unit engaged with the hollow portion of the insulating substrate. With these arrangements, the passive component structure can include only one coil and be configured into an inductor, or can include two coils and be configured into a transformer. Therefore, the passive component structure has the advantages of having simple structure, reduced volume and improved insulation, and can be flexibly applied to make different electronic elements at reduced cost.