PURPOSE: To prevent the heating and breakage of transistors, by bypassing and turning off the base current when the voltage of each transistor in parallel connection is at the predetermined value.
CONSTITUTION: In a switching regulator, transistors (hereinafter referred to as Tr) 1∼2 are mutually connected in parallel. It is driven and controlled with a drive circuit 5 and switching devices 6∼7 through an output transformer 20 and a rectification device 21. It feeds the current to a load 22. Each transistor 1∼2 turns on and off at the same time to control the input to the output transformer 20. At this time when the difference in current is caused between Tr 1∼2, the base current of the Tr for which the current increased is suppressed and the difference in current reduced. When the current increases much more over the predetermined value, the base current of each Tr 1∼2 is bypassed and Tr 1∼2 are turned off.