An overcurrent detection circuit installed in a host for supplying power to a device is disclosed. The overcurrent detection circuit includes: a detection resistor disposed on a power supply line; a current monitoring unit that compares a detected voltage that is a voltage drop across the detection resistor with a variable threshold voltage and asserts an overcurrent detection signal if the detected voltage exceeds the threshold voltage; and a control unit including a timer. The control unit is switchable among (i) a first state where the threshold voltage is set to a first value that is in accord with a reference value for overcurrent protection, (ii) a second state where the threshold voltage is set to a second value that is greater than the first value, and (iii) a third state where the threshold voltage is set to a third value that is less than the first value.