PURPOSE: A semiconductor package is provided to improve the structural stability and reliability of a semiconductor package by using an underfill resin layer. CONSTITUTION: An outer circuit layer is formed in a base substrate and includes a connection pad(115) and a circuit pattern(117). A solder resist layer(120) is formed on the base substrate. The solder resist layer has an opening part for exposing a part of the circuit pattern. A semiconductor chip(130) is formed on the base substrate. An underfill resin layer(140) is formed between the base substrate and the semiconductor chip.