A power semiconductor module has a detector for detecting main circuit current passing through a power semiconductor element. The detector includes first and second circuit patterns; a bonding wire connected at first and second bonding points with the first and second circuit patterns, respectively; and a pair of terminal patterns extended from near the first and second bonding points of the first and second circuit patterns. The detector is designed to detect a potential difference between the pair of terminal patterns generated by flowing main circuit current through the first circuit pattern, the bonding wire and then the second circuit pattern, in order to detect a potential difference across the bonding wire.