Laser diode-driving power supply and laser machining apparatus

A laser diode-driving power supply, comprising:

• a constant current source to supply current to laser diodes;
• a switching element connected in parallel to the laser diodes;
• and
• a control circuit to control the constant current source and perform on-off control of the switching element,
• wherein the control circuit compares a first current command value and a second current command value for controlling current output from the constant current source, and
• when the second current command value input after the first current command value is smaller than the first current command value, the control circuit applies to the laser diodes a voltage in a range of a voltage at which current flows through the laser diodes to a voltage less than a lasing threshold of the laser diodes when there is no output from the laser diodes.