The present power supply device includes a microcomputer that detects a current input to an active filter, a voltage input to the active filter, and a voltage output from the active filter, decreases a target voltage as the input current increases, and controls an IGBT to turn on/off the IGBT to match the input current and the input voltage in phase with each other and also match the output voltage to the target voltage. Thus, as the input current increases, the target voltage is decreased. A power supply terminal can have a voltage with a low noise level.