A semiconductor unit includes: a plurality of transistor chips arranged in a plurality of parallel rows, each transistor chip respectively having a first main electrode on one surface and a second main electrode on another surface; a first conductor layer electrically connected to the first main electrodes of the transistor chips, both corner portions on one end of the first conductor layer being drawn out in a direction in which the rows of transistor chips run; a second conductor layer arranged between the both corner portions of the first conductor layer; and a wiring substrate that is arranged on a side of the second main electrodes of the plurality of transistor chips and includes a wiring layer electrically connected to the second main electrodes of the plurality of transistor chips and to the second conductor layer.