A semiconductor cooling unit for directly jetting a cooling medium against surfaces of semiconductor devices for use in a high-speed computer or the like to effectively remove heat from the semiconductor devices, in which partition members for partitioning a space into regions where semiconductor devices are placed. Each partitioned region has an opening at its ceiling side, and a pipe for supplying or discharging the cooling medium through the opening is disposed so as to project toward a central portion of the back surface of each semiconductor device. This pipe is utilized to also section a cooling medium supply header or a cooling medium return header so that bubbles generated from the semiconductor device surfaces can be smoothly removed, and so that the cooling medium can flow smoothly onto the semiconductor devices.