To prevent any uneven solder wetting in a main surface of electrodes of a semiconductor connected with a main surface of a planar lead and any displacement of the lead vis-a-vis the electrodes due to the reflow of the solder in a semiconductor module having the semiconductor element mounted on a substrate and the planar lead electrically connected therewith, the present invention provides an improved semiconductor module characterized in that the width of at least a part of the region of the main surface of the lead facing the semiconductor element is expanded wider than or equal to the width of the electrodes formed on the semiconductor element, and preferably the other part of the main surface of the lead soldered to an electrode formed on the substrate is split in the extending direction thereof.