1. A semiconductor unit comprising:first coolers arranged in parallel;
semiconductor modules, each of the semiconductor modules being interposed between a pair of the first coolers arranged adjacently;
a coolant discharge pipe provided at one of the first coolers that is located at an end of a stack of the first coolers and the semiconductor modules, the coolant discharge pipe extending along a stacking direction of the first coolers and the semiconductor modules;
a second cooler connected with the coolant discharge pipe;
a reactor interposed between the second cooler and the one of the first coolers located at the end of the stack;
a third cooler connected with the second cooler; and
another reactor interposed between the second cooler and the third cooler.