ELECTRONIC COMPONENT BUILT-IN SUBSTRATE

PROBLEM TO BE SOLVED: To provide an electronic component built-in substrate which eliminates the probability that cracks occur in an insulator layer.SOLUTION: Four first through holes 11d2 and four first through holes 11h2, which overlap with parts of an opening edge VO of a housing part 11a1 projected on a first conductor layer 11d and a third conductor layer 11h in a parallel manner, are respectively formed at the first conductor layer 11d which is the nearest to a core layer 12a where the housing 11a1 is formed so as to penetrate therethrough and the third conductor layer 11h.