A module board has a supporting plate and slender lead pins having their first portions arranged substantially in parallel with one another on a plane substantially coplanar with the supporting plate. The supporting plate and the first portions of the slender lead pins are sandwiched between electrically insulating layer members. The supporting plate and the first portions of the lead pins are isolated from one another with an electrically insulating material between the pair of electrically insulating layer members. Second portions of the lead pins protrude from the pair of electrically insulating layer members. Through holes are provided one for each of the lead pins and through hole conductors are formed on the inner walls of the through holes. Each of the through hole conductors passes through the pair of electrically insulating layer members and the first portion of its associated one of the lead pins and is in electrical connection with a pattern of electrical conductors provided on the pair of electrically insulating layer members, thereby fixing its associated lead pin to the board and electrically connecting its associated lead pin to the pattern of electrical conductors.