Method for manufacturing wiring board with built-in component

A method for manufacturing a wiring board with a built-in component comprising:

• a core substrate preparation step for preparing a core substrate having a first major surface, a second major surface, and an accommodation hole opened at least in the first major surface;
• a component preparation step for preparing a component having a first component major surface, a second component major surface, and a side surface;
• an accommodation step for holding the component in the accommodation hole after the core substrate preparation step and the component preparation step, while the second major surface and the second component major surface are oriented toward a same side;
• a resin layer formation step for filling a gap between an inner wall surface of the accommodation hole and the side surface of the component with a resin layer after the accommodation step;
• a fixing step for hardening the resin layer after the resin layer formation step, to thus fix the component;
• an insulation layer formation step for forming a resin insulation layer on the second major surface and the second component major surface after the fixing step;
• and
• a surface activation step for activating a surface of the resin layer by means of plasma treatment, after the fixing step but before the insulation layer formation step.