P-electrode 30a and N-electrode 31a of a semiconductor device 2, and capacitors 10 in a plate-like shape or a block-like shape respectively connected to U-phase 40, V-phase 41, and W-phase 42 having a switching element 20 and a diode 21 are built in a semiconductor device 2, and a single or a plurality of capacitors 10 are respectively connected to P-electrodes 30a and N-electrodes 31a in each of the phases, whereby the smoothing capacitors are built in the semiconductor device to reduce wiring inductances, the capacitors are miniaturized, and an entire electric power converting device, i.e. inverter, is miniaturized.