A power converter which does not require any separate power source for a switching regulator, etc., and has a small circuit scale and from which electric power based on the positive electrode-side bus of a DC power source can be obtained inexpensively. When the switching element (T1) of an upper arm is turned on, the potential at a point (U) becomes nearly equal to that at a point (P), and a current (ic1) flows in a capacitor (C1) from the positive electrode side of an insulated power source (21) through a diode (D7) so as to drive the switching element (T1) and the capacitor (C1) is charged. The electric power (Vc) of the capacitor (C1) is used as the electric power based on the positive electrode-side bus (P) of the DC power source.
