Provided is a semiconductor device having a small footprint, where the semiconductor device includes multiple power modules and a cooling structure for these power modules. The semiconductor device includes: a first power module on a first top plate of a coolant jacket; and a second power module on a second top plate of the coolant jacket, where the second top plate face the first top plate. The coolant jacket includes a first fin in contact with the first top plate in a passage, and a second fin in contact with the second top plate in the passage. The power modules face each other through the top plates and the fins.