A switching power-supply apparatus comprising: a first power converter and a second power converter connected in parallel; a first output voltage detector configured to detect a magnitude of an output voltage of the first power converter; a first controller configured to perform PWM control on the first power converter so as to equalize a magnitude of an output voltage detected by the first output voltage detector and a target voltage value; a second output voltage detector configured to detect a magnitude of an output voltage of the second power converter; a second controller configured to perform PWM control on the second power converter so as to equalize a magnitude of an output voltage detected by the second output voltage detector and the target voltage value; a first droop characteristic generator configured to generate a droop characteristic that reduces an output voltage of the first power converter as an output current of the first power converter increases; a second droop characteristic generator configured to generate a droop characteristic that reduces an output voltage of the second power converter as an output current of the second power converter increases; characterized by an operation selector configured to make only selected one of the first power converter and the second power converter operate; a first receiver configured to receive from an external device a first correction value for correcting a droop characteristic generated by the first droop characteristic generator; a second receiver configured to receive from the external device a second correction value for correcting a droop characteristic generated by the second droop characteristic generator; a storage unit configured to store a first correction value received by the first receiver and a second correction value received by the second receiver; a first correction unit configured to correct a droop characteristic generated by the first droop characteristic generator with the first correction value; and a second correction unit configured to correct a droop characteristic generated by the second droop characteristic generator with the second correction value. a first power converter and a second power converter connected in parallel; a first output voltage detector configured to detect a magnitude of an output voltage of the first power converter; a first controller configured to perform PWM control on the first power converter so as to equalize a magnitude of an output voltage detected by the first output voltage detector and a target voltage value; a second output voltage detector configured to detect a magnitude of an output voltage of the second power converter; a second controller configured to perform PWM control on the second power converter so as to equalize a magnitude of an output voltage detected by the second output voltage detector and the target voltage value; a first droop characteristic generator configured to generate a droop characteristic that reduces an output voltage of the first power converter as an output current of the first power converter increases; a second droop characteristic generator configured to generate a droop characteristic that reduces an output voltage of the second power converter as an output current of the second power converter increases; characterized by an operation selector configured to make only selected one of the first power converter and the second power converter operate; a first receiver configured to receive from an external device a first correction value for correcting a droop characteristic generated by the first droop characteristic generator; a second receiver configured to receive from the external device a second correction value for correcting a droop characteristic generated by the second droop characteristic generator; a storage unit configured to store a first correction value received by the first receiver and a second correction value received by the second receiver; a first correction unit configured to correct a droop characteristic generated by the first droop characteristic generator with the first correction value; and a second correction unit configured to correct a droop characteristic generated by the second droop characteristic generator with the second correction value.