A multiple-output switching power source apparatus has a series resonant circuit connected in parallel with a switch Q2 and including a primary winding and a current resonant capacitor, a first rectifying-smoothing circuit rectifying and smoothing a voltage of a secondary winding in an ON period of the switch to provide a voltage Vo1, a series resonant circuit connected in parallel with the switch and including a primary winding and a current resonant circuit, a second rectifying-smoothing circuit rectifying and smoothing a voltage of a secondary winding in the ON period of the switch Q2 to provide a voltage Vo2, and a control circuit controlling an ON period of a switch Q1 according to the output voltage Vo1 and the ON period of the switch Q2 according to the voltage Vo2 and limit the ON period of the switch Q1 if the voltage Vo2 exceeds a predetermined voltage.