A printed wiring board mounted with a BGA package including pads, through holes and leads. The leads are linearly formed with almost the same width as the diameter of each of the pads and through holes and thus have high bonding strength against their peeling against an external force. The pads are provided at an angle of approximately 45 degrees outwardly relative to the through holes and along almost in the direction of application of thermal stress, and thus have high durability against their peeling due to an external force.