A power converting device includes upper-arm and lower-arm gate drive circuits which respectively drive upper-arm and lower-arm semiconductor switching elements and which respectively include upper-arm and lower-arm time point detection circuits for detecting time points at which voltages between main terminals of the upper-arm and lower-arm semiconductor switching elements have crossed respective reference voltages, and a controller including a calculator which calculates a change time point of an inverter output voltage and a PWM command pulse generator which generates, on the basis of information about the time point calculated by the calculator, a PWM command pulse to be given to the upper-arm gate drive circuit and the lower-arm gate drive circuit.