Circuit board and its manufacture method

A circuit board comprising:

• at least two wiring layers;
• an insulator layer for electrically insulating said wiring layers;
• a via provided in said insulator layer to electrically connect said wiring layers each other;
• and
• a protective agent dispersed and placed in mottle-like on an interface between said via and said wiring layer to protect said wiring layers, wherein:
• each dimension of said interface regions where said protective agent does not exist is set to such a dimension that a plurality of conductive powders constituting said via may abutted on said wiring layer;
• and
• the plurality of said conductive powders and said wiring layers are abutted each other in each said interface regions where said protective agent does not exist to electrically connect.