The present invention provides a current detection circuit, semiconductor device, and a semiconductor system suitable for improving a current sensing accuracy. According to one embodiment, the current detection circuit 12 comprises a sense transistor Tr11 through which a first sense current proportional to the current flowing through the drive transistor MN1 flows, an operational amplifier AMP1 for amplifying the potential difference of the voltage of the external output terminal OUT and the source voltage of the sense transistor Tr11 for outputting the first sense current, a transistor Tr12 provided in series with the sense transistor Tr11 and to which the output voltage of the operational amplifier AMP1 is applied to the gate, and a switch SW3 provided between the external output terminal OUT and the source of the sense transistor Tr11 and turned on when the drive transistor MN1 is turned off.