A current-source power converting apparatus in an embodiment includes a current-reference generating unit, a polarity determining unit, a PWM-pulse-signal generating unit, and a drive-signal generating unit. The current-reference generating unit outputs a phase current reference and a line-to-line current reference. The polarity determining unit determines a polarity of the phase current reference. The PWM-pulse-signal generating unit generates a PWM pulse signal by comparing the line-to-line current reference and a carrier signal. The drive-signal generating unit generates a drive signal that drives each of a plurality of switching elements, based on the PWM pulse signal and a polarity of the phase current reference.