The present technique relates to a protection circuit for a MOSFET and a protection circuit system including the protection circuit all of which can reduce losses in the main current and increase in the manufacturing costs for ensuring a sense area. The protection circuit includes: a first MOSFET for power through which a main current flows; an IGBT which is connected in parallel to the first MOSFET and through which a current diverted from the main current flows; a sense resistor connected in series with the IGBT; and a first control circuit that controls a gate voltage of the first MOSFET based on a value of a voltage to be applied to the sense resistor, wherein a ratio of the diverted current flowing through the IGBT to the main current flowing through the first MOSFET in current value ranges from 0.018% to 0.022%.
