A semiconductor package and a fabrication method thereof are disclosed, whereby an environmental problem is solved by using external connection terminals or semiconductor element-mounting terminals containing a smaller amount of lead, while at the same time achieving a fine pitch of the terminals. The semiconductor package includes a board (20) including a plurality of insulating resin layers, semiconductor element-mounting terminals (18) formed on the uppermost surface of the board, and external connection terminals (12) formed on the bottom surface thereof. Each external connection terminal (12) is formed as a bump projected downward from the bottom surface of the package, and each bump is filled with the insulating resin (14) while the surface thereof is covered by a metal (16). Wiring (24), (26) including a conductor via (26a) electrically connect the metal of the metal layer 16 and the semiconductor element-mounting terminals (18).