Abstract: A protection circuit, for protecting a protection target circuit from over-current flowing therein without stopping supply of electricpower thereto, includes: a current detecting portion for detecting current flowing in the protection target circuit in form of voltage thereof; a comparing portion for comparing the voltage detected within the current detection portion, or a difference between the detected voltage and input voltage into the protection target circuit, with a reference voltage, thereby to output a comparison result; and a clipping portion for clipping input voltage direct to the protection target circuit, or voltage before being amplified to be input voltage into the protection target circuit by amplification, when the comparison result indicates that current flowing through the protection target circuit is over-current.