To always obtain a constant output voltage from an inverter type power supply regardless of an input voltage level.

This neutral point inverter type stabilizer comprises voltage dividing capacitors C4, C5 connected in parallel between the DC output terminals DC+ and DC- of a rectifier DB for rectifying an AC voltage Vi, a serial circuit of FETs Q5 and Q7, a smoothing capacitor C33 for smoothing an output of the rectifier DB and a drive circuit DR for alternately driving ON and OFF the FETs Q5, Q7; and connects one end AC2 of an AC input of the rectifier DB and the neutral point B of the capacitors C4 and C5. The first connecting condition where single voltage step-up inductor L6 is connected and a lamp LT is connected in parallel to the voltage step-up inductor L6 between the neutral point B and the connecting point SW, and the second connecting condition where a serial circuit K of the voltage step-up inductor L6 and capacitor C12 is connected and the lamp LT is connected in parallel to the serial circuit K, can be changed over.